I used to use nvidia cards, but always assumed video card brand made no difference, since I'd never heard anything to that affect. I recently got my first Radeon card, a minor upgrade that was twice as fast as my old card but used the same wattage (cool, right?). About once an hour, the new card freezes for a full 2 seconds, and maybe 30 seconds later freezes again for half a second. Sounds like no big deal, unless you are playing modern warfare 2, because then you are dead, and your kill-streak is reset. Sometimes I come out of the 2 second freeze to see my avatar ran off a ledge and is falling to his death. Kinda funny, but not when it borks a kill-streak. Getting killed by your video card is just wrong.
I googled around for a solutions, and just found forums full of people lamenting the bad quality of drivers for those cards. It's fine for most games, and it's fine 99% of the time, but that other 1% can be a cruel bitch. Now you know.