[Uh-Nu-Buh]

Just a plug: for developers, the popular Linux variants rock. Fedora Core, for example, comes with everything you need to learn all you could want to learn about MySQL, PERL, Python, Ruby, Ruby on Rails, Apache, etc. ad nauseum. Most of the tutorials out there are centered on Linux, or include Linux. Additionally, they pretty much work out of the box for most desktop applications. And it is all free, and runs well on older equipment.

Caveat #1, I love the MacOS. I just dislike the attitude it often engenders in users, or the attitude of the general person it attracts: hoplessness in the face of adversity. Hep me, hep me, I cain't hep mesef! Contrast this to the attitude linux engenders/attracts: roll up your sleaves, sweat a bit, learn a lot, and get it done. I have a friend who is 19 who just got a mac. He's been a pc/windows guy for years, but loves his mac. One of the things he hates is that he can't even add memory to it, for fear of violating the warranty. He still has his old pc at home for puttering/learning/expanding his consciousness with. He doesn't mess with the mac, just uses it for the 120 (or whatever number it is) things it comes preconfigured to do.

Caveat #2, WinXP is the best platform for gaming right now. I hate it, but I admit it. It has the most game titles, the best graphics performance, the most support for advanced drivers.... Blech. I live with it.