Crank the FSB on that 720 to at least 240. Multis don't mean crap in this game. Once you get it to the 3.2-3.5GHz range you are going to see almost identical performance that you will see anywhere in AMD CPU land. Buy a cooler for now if you don't have 3 spare bills. You will be disappointed.
I was the guy who started talking about the FSB being the significant factor in this game --look in my comments. I have my AMD CPU stuff down. I have had at least one gaming PC with an AMD all the way back to the K6-2. I'm just trying to save you frustration.