Dell Inspiron 5150 Running Hot and VPCs running slow

I had to have a new motherboard in my Dell 5150 laptop, one of the memory slots failed on the old one. Since the repair my laptop seems to have been running hot. Also when using Virtual PC 2004 SP1 the sessions seems to pause for a second or two from time to time.

I have tried the hotfix for VPC 2004 and this seemed to help the speed a bit (but not as much as I would have hoped), but my PC still seemed a lot hotter than it used to be.

I installed the excellent I8KFanGUI to get an idea of what was going on, and found that I seems to always be running at top CPU speed 3GHz, so no smartstepping slowing me down (oftan blamed for slow VPC performance), and the fans seems to be doing sensible things. However, my average CPU temp was about 55C with a max of 71C.

I read round a bit and found a number of people with CPU temp problems with the newer BIOS (A37/A38), so I downgraded to BIOS A35 (which I think my old motherboard had) and low and behold my idling temp dropped by nearly 10 degrees to 47C. My max is about the same.

So at least I don't have to prop up my PC on a book to avoid thermal shutdown, I just need a better solution to the VPC speed problem, I suspect a networking polling issue.