I would love to have him run a VL live CD but he is used to his educational games, and other games (Dora and other kiddie stuff that I can't get wine to run) that open source just can't touch. His computer at home (he's had one since he was two) is dual boot and he gets pretty bored with the kids stuff that comes with Linux.
I figured that was the case. I wish Linux devotees would realize that Linux can't do everything--there are some programs that work on Windows only and there are no Linux substitutes. Have you checked out various kids' Web sites? My grandchildren, who live far away so are not here often, have several sites they like with fun games that appeal to a range of ages. These should work with a VectorLinux LiveCD or any LiveCD that installs Flash and the MPlayer Plugin.
I'm not real familiar with Windows 2000. I've never used it on my systems, but I do take care of four computers for a small nonprofit, two of which are using W2K. I don't work on them often.
If you log in as Administrator you should be able to set up an account for him with very limited privileges. I wish I could give more details, but there are lots of administrative tools in W2K because it is intended as a business OS. I can't imagine that there is not a way to prevent a user from making a system change that would affect other accounts on the system.
You also might want to teach your son to NOT click on everything. That's a sure way to get infested with malware if he goes on the Web at all. He may as well learn safe computing from the start.