The new 8800gts is coming out with the new core and that should run better than the 8800ultra. So i would wait a month for that. Or if you want to buy a card now i guess a 8800gtx or 8800ultra.. or you can go SLI and get 2 8800gt cards for $270 each and they would be a lot better then a single ultra
Whatever you buy for $600, it had better be BRAND NEW... no card that's been out for months... you're paying a premium to buy a card at the top of it's game... no reason buying a card that's about to be passed by a card released next week/month. That said... I wouldn't buy an 8800 GTX/Ultra just yet... they've been out for a while and you'll feel like an ass when they're quickly passed by a new card. This process will inevitably happen... you just don't want it happening the day after you buy your card. That said... I'm sure others would agree that EVGA's step-up program would offer some degree of insurance against this.