117C is bad..I guess XFX really researched "computer component melting thresholds"..and incorporated them in the 8600GT...though I have a 8500GT by XFX and it too used to heat up...used to idle at 80C. I was worried about that..banged my head a bit..then finally mounted a after market cooler.
If you dont get a replacement and want to keep the 8600GT (is a good card)...go in for an after market cooling solution...cause no use holding onto the warranty since they are not replacing it..!!
FYI:
A friend of mine also just got a XFX 8600GT...without consulting me first...he will have a nice summer I am sure...
Best of luck...though would suggest..be careful..you might damage the card.