Probably not you current problem but 2GB RAM is really not enough for Windows 7 64bit. seriously consider upgrading it.
As mentioned above, install HWMonitor and post the temps back here.
If it turns out to actually be that your temps are normal, then I would recommend testing the memory next with Memtest86 via a bootable CD.
The results from these will point us to other possibilities to follow up on.
You have to be a little bit crazy to keep you from going insane.