I just love the desigh and this is on my want list.
I hope to have the Profile 1, Pro 2, Pro 3, Pro 4, Pro 5, and Pro 6 one day.
Give him a break, he's 12 after all. Pretty cool computer, Gateway's copy of the Apple iMac. The GP3 that you linked to should run XP great with it's 1 GHz Pentium III CPU and 512 MB RAM. XP is based off 2k, so any necessary drivers should work. Trial and error will find out.
I've always like Win2k anyway, used it up till I finally bought an XP Pro disc in 2006. You can easily upgrade 2k to XP, but know that Win2k Pro can only be upgraded by WinXP Pro.
You'll be all set up, then. I personally hate upgrading Windows, I usually do clean installs, but that's up to you.
Have fun.