Depends how much you want to spend on a GPU. You could do a 260/275/285/295 or all the equivelants in the ATI flavor. If you've got no budget go for the 5970 ;) That heatsink you picked also requires extra mounting hardware for 1336 just so you know. This one does but no fan included:
NCIX.com - Buy Thermalright ULTRA-120 Trueblack REV.C 6 Heatpipe Cooler LGA1366 775 AM3 Heatsink *Fan Not Included* - TRUEBLACK120 Rev.C In Canada.
I'd go for the Corsair H50 though. Everything else seems ok though...