Before Vista I was running an ATI Radeon x1300 which was pretty awesome...
Sadly *at the time" ATI Drivers had major issues with Vista when Bought it.. I ended up updating my system to a Dell and it came with an Nvidia gforce 7300..
It runs Great on my system and so thats what I am running..
I was a long time ATI fan but now I like BOTH...
Its hard to say what is better.... Everyone has "their own opnion"

But yeah for now I am running Nvidia..