I've used probably half a dozen Linux distributions extensively, another half dozen enough to have a pretty good understanding of them (enough to know why they aren't as useful to me as others, at least), and know a fair bit about another couple dozen without having used them much.
I've written a few articles here at TR that could be helpful for the Linux beginner:
[url=http://articles.techrepublic.com.com/5100-10877_11-6106234.html]Linux 101: Use Knoppix to resize partitions for dual-boot installs[/url]
[url=http://articles.techrepublic.com.com/5100-10877_11-6105410.html]Linux 101: Installing Debian GNU/Linux[/url]
[url=http://articles.techrepublic.com.com/5100-10877-6102898.html]Linux 101: Making manpages work for you[/url]
[url=http://articles.techrepublic.com.com/5100-10877-6104158.html]Linux 101: Efficient software management with the Advanced Package Tool in Debian[/url]
There's more where that came from, too -- several articles about data and network security, for instance -- at [url=http://sob.apotheon.org/?page_id=7][b]this page[/b][/url]. It isn't there today, but it's likely that there will be an article about using Subversion for personal document management listed on that page in the next few weeks as well.
I intend to get to work on some resources more related to FreeBSD as well, in the near future.
In my experience, RPM-based distributions vary wildly (at least, about as wildly as can be expected in the Linux world) from the expectations of most users of unixlike operating systems. If you want general Linux knowledge, RPM-based distributions are probably not the way to start, as RPM-based distributions not only vary quite a bit from DEB- and source-based distributions, but also from each other. If you just want to get away from Windows, though, and don't care about comprehensive understanding of Linux in general, that's not a reason to avoid RPM-based distributions.
(note: RPM and DEB are binary package formats -- RPMs were invented by Red Hat, and DEBs by the Debian project)
RHEL (Red Hat Enterprise Linux) and Novell SuSE provide the best support for proprietary software on Linux, such as Maya, with RHEL providing better support than Novell SuSE, because proprietary software vendors tend to develop for a specific platform rather than for portability. Fedora, the community-based spin-off of RHEL, is similarly well-supported by proprietary software vendors.
Gentoo, Slackware, and Linux From Scratch provide the best support you're likely to get for nonstandard software configurations -- LFS is the most customizable, Gentoo is the easiest to configure, and Slackware is somewhere between the two. All three of them make it easier to thoroughly break things than most other distributions, however, because they way they provide this configurability is through use of source code compilation, with compile-time configuration options, to put together the platform. Gentoo is notorious for its "KDE is broken this week" issues -- which are not as bad as some make them out to be, but can be frustrating. Slackware is quite stable, but you can screw it up pretty easily if you're not careful -- at least you'll know it's your fault if it breaks, though. LFS is not for the faint of heart: unless you want to really get your hands dirty with experimentation and learning about the ugly guts of Linux, use something else.
Knoppix is the biggest name in LiveCD distributions. MEPIS is more of a "professional" LiveCD. Ubuntu's LiveCD is mostly valuable as an introduction to Ubuntu. Those are pretty much the biggies for LiveCD distros -- there are of course other, more niche-oriented LiveCDs available, such as Zen Linux (really nice, lightweight, elegant desktop, but not nearly as good for hardware support as the others I've mentioned).
There are the Windows-replacement commercial distros, of course. These include distributions like Linspire and Xandros. I tend to recommend avoiding Linspire -- use Xandros instead if you must use one of these. Some of the software provided with these is proprietary, and to get the full version of one of these distributions you typically need to pay some money (a pittance compared to Windows licenses, however -- and compared to support costs for RHEL and Novell SuSE as well).
PCLinuxOS is sort of like a community version of the commercial distros Linspire and Xandros. It's a "user friendly" Windows replacement distribution, with a "user friendly" community. I have yet to meet a PCLinuxOS user (in the sense that he uses PCLinuxOS first and foremost) that doesn't come off like a Kool-Aid drinking cultist, however. Fully half the Linux users I've come across who are obsessively anti-Microsoft and sound utterly unreasonable about it (as opposed to those who are quite reasonable) are PCLinuxOS users as well -- and I don't think I've met a PCLinuxOS user who doesn't fit that description. I don't know why those personality traits are so constant for PCLinuxOS users, but they may be worth considering as factors in your decision.
Debian has long been my favorite Linux distribution. It's among the most stable, and among the most easily configurable without being a source-based distribution. It has more software in its standard, free archives (about 20,000 distinct packages) than any other operating system on the planet -- about seven times as many packages as in Fedora, for instance. It has the biggest community of any OS as far as I'm aware, some of the most competent Linux users, and some of the best software management tools (the Advanced Package Tool, Synaptic, aptitude, and so on). Whereas RPM-based distributions have a tendency to change the way they do common, standard things, so that it's typical for any two established RPM distributions to differ from each other in occasionally surprising ways, the vast number of Debian-based distributions (including Knoppix, MEPIS, Ubuntu Zen, and a slew of others that I haven't already mentioned) tend to stick to pretty much the same way of doing things so that skills you learn that would be distro-specific with RPM-based distributions are more widely applicable with DEB-based distributions.
Then . . . there's the BSD family of OSes.
NetBSD was once the most widely ported operating system around, but Debian has outdone it on that score.
OpenBSD is still the most secure OS in existence. It has shipped with a grand total of exactly one remotely exploitable vulnerability in default configuration ever. Ever. Just one. When you consider the hundreds of remotely exploitable vulnerabilities in default configurations of MS Windows [i]every year[/i], as compared with OpenBSD's one single vulnerability in the same fifteen-plus years, that should give you a pretty good idea of how secure it is. The OpenBSD project is also the source of a lot of security software projects, such as the OpenSSH remote access secure shell tool that is distributed with basically every Linux distribution and BSD OS in existence -- and is a better SSH implementation than any commercial implementation I've seen (and there aren't any other free implementations that even come close). The downsides to OpenBSD lie in hardware support, software support, and performance: it doesn't support anywhere near the hardware of NetBSD, FreeBSD, and most Linux distributions; it is somewhat limited in what software it supports, but the software it does support it supports exceedingly well; under high loads, it benchmarks notably more poorly than NetBSD, FreeBSD, and standard Linux-based OSes. For low-load purposes with fairly standard, productive uses, OpenBSD is quite useful. You just need to be aware of its limitations when choosing whether or not to use it -- an OpenBSD box (as OpenBSD currently exists) will never be much of a game machine.
FreeBSD performance is comparable to Linux distributions using a 2.6 kernel -- which is to say it's excellent. Hardware support is not quite as broad as Linux, but the stuff it supports is often easier to configure and use with FreeBSD than with Linux, in my experience of the last four months or so (sound configuration, for instance, is a no-brainer in both when everything goes smoothly, but when it's not quite as smooth it's a lot easier to fix in FreeBSD than in any Linux distro I've used). Whereas Debian has more software in its archives than any other OS, FreeBSD is a very close second, and I don't think third place is anywhere near Debian and FreeBSD for software availability. FreeBSD, however, does not support proprietary commercial software as well as any Linux distribution. In many cases, where there's a gap in software support between FreeBSD and Linux, the difference is made up by excellent support for Linux software compatibility in FreeBSD, using compatibility libraries much easier to use than the Wine compatibility libraries for MS Windows software. FreeBSD supports installation from both source (via the "ports tree") and binary packages with equal facility, as well as Debian does with packages and Gentoo with its own ports system.
Generally speaking, the best enterprise servers are, in order, FreeBSD, Debian, and RHEL. The best desktop for easy migration from MS Windows is probably Ubuntu, but it suffers some issues with stability and security as compared with Debian (then again, since Debian's about the best of any Linux distribution for those purposes, that could be said of any of them). Debian is likely the best general-purpose workhorse distro, at least as far as my tastes are concerned, with some of the lightest system administration demands.
As for documentation . . .
It's kind of a toss-up between FreeBSD and Debian, as far as which OS has the best documentation. Gentoo and Ubuntu are getting to be neck-and-neck for online forum support, but neither of them has anything as comprehensive as either the FreeBSD manual (freely available on the website and with the OS) or the Debian manpage system (also, freely available on the website and with the OS). Each has its advantages. FreeBSD also has extensive manpage support, but not quite as extensive as Debian's; Debian also has additional documentation, aside from the manpage system, but not quite up to the integrated, comprehensive standard of the FreeBSD manual. RHEL and Fedora have by far the most extensive documentation support via published books you can get in bookstores, though BSD-related books tend to be better organized, better written, and more complete.
Despite all these differences, at least 98% of the skills you learn with any of these free unices are transferrable to the others. Even OpenSolaris is probably about 95% compatible with Linux and BSD OSes for transferrable skills -- more so, if you run it with BSD or GNU toolsets.
Hopefully that answers some questions. I'm sure it raises a few more.
Thanks for the compliment, TiggerTwo, and thanks for a Linux-related thread outside of article discussion that isn't a flame or a troll for flames by a Windows fanboy.