A small tip that worked for me - When the game is running, pause it and open the task manager. Find the rfg.exe process, and check its priority. For some reason, it seems to default to above normal. When I put mine back to normal, everything ran fine after that, no matter what I blew up and how.
Give it a try, and see if that works for you. If it does, the only bugbear there is that you might have to do it each time you run the game. but hey, it runs fine on my E6600 with 2Gigs when you set it like this.
Be warned though, ymmv, so you might not get the same results. Worth a try though.