Alright so the GTS's you picked spacebandit72 are old, pretty old. They're build on the previous G80 core and are more power consuming, heat producing and in case of the GTS's also less performing. You will want a new card for good performance (not that they perform crap, the old GTS's), and because they're not more expensive anyway. The G92 (new core) GT is better than the old GTS, the new GTS G92 is better than the new GT.
Look at it like this going from top performance to lower performance:
G80 GTX/Ultra are on top, but also very pricey (and in some cases outperformed by the new G92 GTS, but because of lower memory amount and bandwith on the new GTS, the GTX/Ultra still win)
Then theres G92 GTS which is a very decent card, just a little less performing than GTX/Ultra but extremely good for the price.
Then there's the new G92 GT, which is a little worse than the GTS but still good and a perfect price/performance ratio.
And here you get the old G80 GTS's with 320 and 640 MB... They may have higher core clocks or higher amounts of memory, the new core technology on the GT/GTS still wins from them. And besides, theyre not more expensive anyway so in conclusion:
Get a new G92 GT/GTS with 512MB, and don't buy the older GTS's with 320 and 640MB. They won't run Crysis on high, and a single G92 GT/GTS won't do it either if you are playing on larger resolutions, but no PC at the moment can play Crysis maxed out. It will still be decent though.
End of speech, lol.
