id recommend getting the 1 gig versions, the limited memory hold the 768 ones back a lot. it depends on your resolution and the game, but 460's in sli are usually second to nothing besides the 5970, and then obviously dual cards of higher performers. and any dual card setup runs into hassles, there CAN be overclocking hassles, driver hassles, compatibility hassles, just a lot of stuff can go wrong. its always better to get a single card over dual cards, but dual cards usually beat the stronger cards when doubled up, and give better
value. personally, id wait until the 475 is out, evaluate it, see what it can do, then move. the
gtx 460 is still in its infancy, wait for the rush
to stop, prices to drop a tad bit, and better performing versions to be released. currently, 1 gig versions are harder to get, but as time goes on, more will release them.
The 768mb is what had me skeptical and even with scaling at ninety percent it still had me wondering. I run all my games at 1920x1200 max settings so maybe I will just go for A single 480 for that reason but I also can wait a little bit, my current gtx 280 just seems to be performing really lackluster right now..