Every time I use XP I find something else to hate about it. Last night it was file and print sharing (brand new XP laptop will not share with old XP PC upstairs at my mate's house), earlier that day it was general un-responsiveness which resulted in a four-second press of the power button to force a reboot. In work I also find file sharing with XP a complete non-starter (XP can access a 2000 PC, but nothing can access an XP PC). I'm amazed XP is on the shelves at all, as far as I'm concerned it's still not fit for release.
When I bought my CCTV PC (a Dell Dimension 5100) XP survived as far as the EULA that appears first time you boot it. XP off, 2000 on, works perfectly, shares files happily with my laptop and other PC, no problem whatsoever. As far as I'm concerned if software requires XP, I don't require that software and will look elsewhere.
For me it'd be a close call between a PC running Windows 2000 and a Mac, but given the choice between an XP PC and a Mac, I'd go for the Mac every time.