I like my gigabyte 6600. It's oc'ed to 535/650 right now from 300/550 stock which gives me framerates damn close to a 6600gt and newegg has them in stock for only $115.
The thing is a lot louder than I'd like it to be though. I'm still waiting on the gigabyte turboforce line so I can swap this 6600 out for one with a passive cooling solution..