They will be ok for most stuff.
It will at least 'play' crysis on LOW settings, but unfortunately some games like Rainbow6 Vegas, etc it won't play at all due to the requirement of an SM3.0 compliant card.
It's solid , but I'd recommend the other options I listed if you want to play 'big games' (ie Crysis, Bioshock, COH, COD4, etc).
If you're lucky and the PC has PCIe slots, you canget a much better gaming card for about $60 on NewEgg.