I got the asus 4850. I'm just going to wait a little bit for any new bios revs or drivers to help things out before i get an aftermarket heatsink. The asus came with a utility that allows you to tweak the fan speeds based on various temperatures.
Right now it's very quiet and idles around 59C. I still need to do some more tweaking though. While i'm playing cod4, the fan will speed up a little bit to compensate for the temperature.
That's not too bad, but every now and then, it will just go full speed and scare the Crap out of me. So, i just gotta up the threshold for where the full speed kicks in.
Outside of this, AMD has already stated that this GPU is designed to operate at the hotter temperature. My problem now is just to keep the fan from getting too loud.