My X1600pro is about 38c idle and heats to low 50's under high load. Highest temp ive seen on mine was 58c and that was when i wanted to see oblivion maxed. I can tell you it didnt run so well
A recent application of Artic Silver 5 (...or is it 6), replacing the stock crap (can I say crap?) had lowered my Sapphire ATi x1600 Pro GPU idle temperature from 74 C to 66 C. (That's still pretty bad though as it reaches 90 C under a load.) I'm planning to replace the stock cooling with an aftermarket cooler. Did the sam thing with my CPU and it lowered the temp six degrees. (From 44 C to 38 C....)
(....although everyone is entitled to their opinion, I think ETSA is crazy with his answer [+120 C]. I don't even know why I put that option....)
In these hot days, avarage idle temp jumped from 35°C to 45°C, after hard gaming, before I didn't see it go past 60°C and now it's hits around 75°C, vid card in signature.