If you plan on playing Crysis in Vista, run it in DX9 mode ALL HIGH for now. It looks the same as ALL HIGH for DX10 anyway. Looks great and runs on average in the high 30's low 40's at 1680x1050 res.
The only problem I have run into with my 4870 is that in DX10 Crysis there are little white dots in some textures in some of the buildings in the game. This bug is known to ATI and they are working on resolving it. But this is ONLY DX10 mode of Crysis.
I have not seen it anywhere else.
My current list of games that seem to run glass smooth everywhere with details maxed out on my res of 1680x1050 are...
Call of Juarez
Half Life 2: Episode 1 and 2
Race 07 (Although with HIGH shadows the replays still have random hitching on some maps like my 8800GT did. Game bug I think.)
Overall I like this card alot. My favorite since the 8800GT I picked up last year.
As far as 80C idle goes... That is how it is designed. ATI was gunning for near silent running.
It runs cooler under load than my 8800GT and my case temps are lower since the card expells the hot air.
Another plus was it was happy with just a good old 500 watt PSU.