PCLinuxOS > All.
Although I do think they coulda come up with a better name,
I say go with xp. Vista looks pretty, very pretty...but I fail to see any justifiable advancements that make it worth the extra money over XP. I'm really drawing comparisons between windows95 and windows 98 here. And conversely 98 to Millennium. Just not worth the coin yet. If they had at least busted out the new FS this mighta been a good enough reason, but that project may never even see the light of day!
So far I can do everything on Linux that I was able to do on windows. I play World of Warcraft, watch dvd's, do the whole web thing, play mp3's, the whole nine. All for free. With a Journaled Filesystem to boot.
Fedora is good stuff to IMO, but I hear the multimedia stuff like dvd playback is a bit difficult, I know it was the last time I used it...