Thanks, guys -- great responses. That pretty much answers my questions, but it did raise a few more.

1.) pludi, I was curious what you meant when you said "But I suggest setting up the new system on different hardware, since it won't be as much trouble should you need to re-install." Maybe I'm just being thick, but I can't figure out what you meant by this. Could you elaborate if you get a chance? Thanks!

2.) There were two recommendations for OpenSolaris in these posts. I can probably research this myself, so don't spend too much time answering this, but what is the difference between Solaris and OpenSolaris. I assume the main difference is that OpenSolaris is open source, but what exactly does that mean? I mean I know the technical definition, that the source code is available to read and alter if you want, but what does it mean in terms of the operating system itself? Does Solaris have functionality that OpenSolaris doesn't, or vice versa?

3.) jp, you mentioned this: "And why buy when all the great ones are free. You buy when you want more support than you get from reading man pages and asking question in places like this." This is a very good point. Is this true, that the only thing you get more of when you buy it is support, and that there's no real difference in functionality? If that's true then I would definitely be inclined to go for a free one.

4.) The OS's I've been considering are RedHat Linux, Fedora Linux, Ubuntu Linux, Solaris, and BSD. Given the information I gave in the last post (about being a developer and whatnot), should I cross any of these off the list, or should I add any new ones to the list? jp mentioned CentOS -- I don't know anything about this one. I definitely want to have a lot of languages available to develop with (like pludi mentioned about Linux). So I guess I'm just asking if anyone has any further input on this. Other than that, thanks a lot for your replies -- they are very much appreciated.