@benneh:
I still don't understand that your memory is "too fast". If you want to change the option for memory speed, you can set it in BIOS. Find something like "DDR2-1066" or PC2-8500 etc. Try different settings.
But I think it's not a memory problem, it may be a Windows problem. To confirm that, run Ubuntu from a live CD. Ubuntu is a Linux Operating system, which you can run directly from the CD without having to install. Download Ubuntu Live CD from here:
http://www.ubuntu.com/getubuntu/download
Burn it and boot from it. On the options screen, select "run ubuntu without installing". Wait for sometime (may be upto 10-20 minutes). If it runs fine, it's not a RAM problem (because a hardware problem would affect all the operating systems) and you need to seek support in the Windows support section of TSF. If it doesn't run fine, it's a hardware problem.