For sure, the networking model is better in Win7 (seriously, how many times have you clicked on a network folder only to completely and utterly freeze Explorer.exe?), and probably things with security and user management too. And probably many other things I've used that I can't think of right now.
Curiously, I don't see people screaming, "the sky is falling, get Win7+ now!!!!1", so it's probably not terrifically bad to keep on using XP, given responsible use and support (current updates; firewall at router, computer or both; don't download and run random EXEs, or Office files, or...). Thoughts?
Tim