I used to be a BIG AMD supporter--but I switched to Intel when I did my Dual Core box that I'm currently running on (until tomorrow!). I'm really liking the Intel performance at this point in time, and they are continuously recommended to me over AMD.

My new build is using the Q9550 CPU, along with 8 gigs of RAM and Dual Radeon 4750s. IMO, I would go for the Intel. If you are concerned about cooling, you won't have ANY issues with the Antec 900 case. That is my current case and it flat stays cool. My husband switched to a 900 case as well in his most recent build (we were having lots of issues with his PC overheating), and we've had no issues since that replacement.