The batmobile coolers on the new 58x0 series (and some 5770s) are supposed to be quite good.
And they look way cooler than most aftermarket coolers I've seen--I hate to admit it, but that's part of the reason I want a 5870...
I just bought an eVGA nvidia 260 (core 216) to replace an ATI 4850.
The ATI has a brutally loud fan. The eVGA does much better even under load, though i am considering getting something other than the stock fan. I replaced the fan on a previous 9600 GT card with a large passive Zalman; no noise and the card worked perfectly fine, though no overclocking was ever attempted.
GPU temps stayed below 60C.
