Solaris or WIN2k

Simple answer is there is no one answer.

Solaris' advantage is that it has all the benefits of any unix including good multi-threading and gets the most performance out of a server.

On the other hand if your org doesn't have UNIX techs then you would have to hire or train one.

Windows 2000 has the advantage of being easy to use and set up. And its supported by a huge company and all things being equal its hard to find an area where you can't get software. But it does have alot of overhead which means you won't get the same performance levels on the same box running a Unix variant.

Boxes are usually cheaper than techs. If you already have someone inhouse who has time to support another Unix server great. If not - think about the fact that you can buy a couple of medium sized servers for the annual salary of a good Unix tech.

James

If you can afford the time/resources try both of them out. Either in parallel on similar boxes doing similar tasks or dual-boot (using a tool like System Commander) on one box.

The real issue as I usually see it: which one works better for your situation? Which means that you'll need to devise a testing strategy which is "fair" and tests what really needs to be tested, for the work you intend to get out of the boxes.

Good Luck.