Like I mentioned in the 7 page dribble thread, I said you should wait for the 4770. If its just for a "backup" PC for gaming then I wouldnt dump $260 on a video card.
As for the topic, ive gotten my GTX 285 stable at around 760 core, but I keep it at the EVGA FTW specs, which is 720core/1651 shaders, and 1386 memory. No artifacting, and temps are doing alot better since I redid my case this weekend, load temps droped about 4c. 760mhz core was just too high for comfort, plus I admitedly didnt let it run stressing for too long....was nervous.