XP is definitely the most stable OS I’ve used from MS (out of 3.11, 95, 98, 98se, ME, and limited exp. with 2k). I think the most stable I’ve ever used was OS/2, as I don’t recall it ever crashing on me, and I’ve had problems with Linux, though that may have been more hardware/driver problems.
XP has crashed a few times on me. I often got the blue screen of death with my old 3dfx card. Once I got a GeForce 2, that almost went away. I have had IE and other programs crash on me, but usually it didn’t crash the whole system, just the individual programs.
Another advantage of XP… since it appears that your system will be used by more than 1-2 people, XP has a bit more multi-user capability than other home Windows versions. Each of your family members can have their own user ID, get their own “My Documents” folder, and their own desktop. Also, if you need to jump on and do something, you can just log out of them, and into your desktop easily, their stuff stays in the background, and they can pickup where they left off when you’re done… I haven’t needed this though, since I’m the only user of my 3 PCs, and I never use the “family” pc. This is more cosmetic and for ease of use than for security… but if you can’t trust your family, who can you trust? hehe