Cybercore, just to answer to your post.
The computer worked fine with an earlier version of bios when it was running on both cores, but that didn't last long, a day. When it restarted I couldn't get the other core going anymore, updated the bios and...well, slow to snail.
And I did reinstall win7 after the bios upgrade, three times, but it spent hours and hours doing it, so I just stopped bothering. the problem with speed happens when I'm installing windows. I tried installing win XP and that was excruciatingly slow, and the system was built for XP, so its almost definitely a hardcore problem. The motherboard I'm guessing.
If you figure out anything, please keep posting, I'll be keeping an eye out.