It's Random crashes,it sluggish performance,And it's graphical bugs! I mean,Even microsoft has problems with it:
(Taken from installation):
Im Reinstalling it on my new rig,to see if it's still worth selling it on ebay.
Wow,It's like microsoft WANTS to be pirated,I have bought windows once,had problems with the license,so i went with a pirated version,and it worked better than the original.
Edit; Its telling me i have exceeded my limit of installing with this license,I have installed it 3 times (Installed once,then installed becasuse i upgraded to vista,and then installed it after i reinstalled XP)