You have a zalman cooler and your 7800 runs *that* hot?? Are you in the desert or something?
Did you check the contact that HSF is making with the core? Ramsinks properly installed? Is your 7800 overclocked at all??
I mean FYI when I was in an apartment with poor air circulation my 7800GT would idle at 46C and load at 66C
Now in a place with good air circulation I idle at ~36C and load at 55C all on the stock cooler....