If you have stability issues with 2k or XP.. (XP more specifically) its most likely due to bad-hardware, over-clocking, or bad drivers. XP is incredibly stable.. All I can say is, my system has crashed twice since january when I installed XP. Once was from ATI drivers blue screening me.. and once from when I tried to play half-life.. (heh)
Once you disable un-needed services, my XP takes only 63megs of memory (as indicated by taskmanager) on boot. I dont think I have been able to get 2000 that low yet.. maybe 65megs.. So XP really isnt bloatware..
XP boots usually somthing like 15 seconds faster then 2k pro.. and if you run bootvis it can be even lower. I managed to get a duron 800 with 256megs PC 133ram and a 10gig 7200rpm harddrive to boot to a usable state in 12seconds.
XP's theme feature is very nice. 
www.themexp.org
XP's driver set is also significantly larger. I couldnt get my soundblaster to work properly in 2k..  but it works without a hitch in XP. Along with my USB burner.. Doesnt work at all in 2k.. yet it works perfectly in XP.
2k works good enough for many.. but in my eyes, XP is much better.. I guess it depends on what you like really.. just like anything.