I have the PNY Verto PCIE 6600GT, and so far it is very good. Although.... I have only played it with the original Deus Ex, but its your lucky day if you really want to find out about it, as I just bought the HL2 special edition, I havn't put the dvd in yet, so I don't know if this steam thing really really takes hours to do, but if there is anygame that should be used for testing a card, you can't get better than HL2, right?
I'll tell ya, its good to play deus ex with no slow down and all the settings all the way up
Its age does show through though, but I havn't finished it yet is the speed it used to run on my old pc was almost unplayable.
BTW, any tips on setting up a 6600GT for half life?