My exp with XP (lol), I had problems with the drivers it supports.
For example, I couldn't get drivers for my soundcart anyware.
Micro$oft knew the problem but no solution.
Company of my soundcart (lost the name) knew the problem but no solution.
The same with PB.
Via the PB forum I got to a site where they had the drivers...
It didn't support my ADSL modem ether and my keybord.
After that, it was pretty nice, but if you have 2000 (it's the almost same) I woudn't go for it.
If your windows(any version) works fine, then why go for XP?
There are some changes that are nice, but nothing great...
Conclusion: looks nice but the inside is still the same