Running the 7800GTX at 490/1300 with the CPU X2 4200+ OC'd to 2600, I get idle GPU temps at 60, and full load while running EQ2 or CoH of 75. Case temp is 61, and CPu temp is 60 at idle, and maxes out at 64 under load. I have all cool and quiet and powersaving stuff turned off.
I use the Nvidia Monitor utility to see the temps.
I have this all installed in small tower case, with 4 hard drives and 2 CD/DVD drives. So it's a little packed in there.
This evening I'm going to open some of the stupid case places that they drill holes in the case as the "vent" for the fans to suck and blow air through. On previous cases that had a large impact on cooling.
I'll update this with changes in temp after I cut open the places for the fans.
To the OP. Nvidia's max temp before throttling the GPU is 115, so if you are at the low 80's as your max, though it sounds high, it's still a ways below where the card will throttle itself. If you aren't seeing graphical glitches, or getting slowdowns in heavy graphical games, I wouldn't worry to much about it.