Linux

That the big makers have not to sell, supply or support any form of Nix over Windows.

Paying M$ a License Fee for not supplying Windows isn't an Option for most of these people as they are tied up with M$ so tightly that there is no way around this for them.

Col

Dude, Dell does indeed sell Linux capable hardware, I've even seen a few online
ads for Ubuntu preinstalled. Why did you even bother posting this as a question,
since the answer is not what you want to hear anyhow.
I don't defend Dell, HP, Acer, etc, they make their own decisions as to which OSes
to install and support. IMO, Col was too nice on this one, and the thought of marking
your Q&A as spam has entered my mind, but I didn't.
A little research can go a long way...besides, you weren't interested in purchasing
anything at the Dell store were you? Just looking for a place to say "Look at me,
I bought a Mac!" Go practice your OS religion somewhere else, like the Apple forums.

Dell was the first of the major mfgrs who offered Linux or Windows way back when Red Hat was about to go public. 1997 or 1998? You could order either or but not both. Although I am not certain, I do believe you can still purchase the servers with Linux pre-installed.

there are articles about the Dell xps 13 ultra book coming out with a Linux version on it for developers. (i do not defend dell, but you have to be fair , as all the other responses say, just do an internet search or go to dells website.)

I know that HP does indeed sell business models of their laptops, desktops and workstations with a choice of OS. They do this in order to accomodate businesses, governmental organizations and schools that use alternate operating systems in their organization. HP offers both Free Linux or Free DOS. On the consumer laptops and desktops HP only offers Windows so they only have to support a single OS.

Dell only supports linux on their server line, and then only Red Hat Enterprise and Suse. They did have a program a few years ago where they were shipping some desktops and laptops with Ubuntu, but they got so much flak from Microsoft, that they finally dropped it. MS truly has a strangle-hold on the manufacturers for desktop OS priority. As for markp24's comment, I wouldn't hold my breath on that happening anytime soon, and if it does, it will most likely be a short-term offering. If you want an alternative OS, you either have to buy Mac, build your own, or wait for the warranty to run out on your current box and then install whatever you want.

If you ask a Dell Rep to quote the Lattitude or Optiplex you can get Linux. Of course you cant get it on the consumer products.

This is a no brainer. Boot the Windows computer with a Linux live CD; you will be given a choice to erase Windows or dual boot the Linux along with the Windows. Choose the latter; subsequently when you boot the Dell you will be asked to choose which operating system to load.

Second option: Erase the Windows and boot from the Linux live CD to load Linux as the only OS on the computer.

Third option. Keep the Windows, download a Virtual Machine Program which runs in Windows and load Linux into the virtual machine. This is how Windows 7 works in "Windows XP mode".