This should be a good one because opinions are like mouths everybodys got
one. With that said, I use an ATi X1900GT and it works perfectly fine with
Vista and Aero desktop.
From what I've been reading I'd stay clear of the Nvidia cards right now
until Nvidia puts out final drivers for vista. ATi has already put out
their working final drivers for vista and I don't notice any performance
issues so far.