Do you have a Microsoft Windows PC running slow? The first but usually most painful solution is to reformat and or reinstall.
However before proceeding with such drastic steps there are two things I recommend checking:
1) Do you have enough physical memory? You want to reduce the frequency of virtual memory paging activity. Run Task Manager by pressing CTRL+SHIFT+ESC. See below:

*Note: If you have Windows Vista or 7 remember you can add additional member on the fly with a USB stick by using ReadyBoost
2) Make sure your hard drive(s) is running in DMA mode. It is unfortunately not uncommon for Windows to revert to PIO mode which means transfer speeds of 3-4mbps instead of 50-60mbps. Basically remember that PIO=slow, DMA=fast. Open Device Manager by pressing WinKey+R and typing “devmgmt.msc”

#1 by Mike on December 14th, 2009
Quote
How would you do this on Vista? I have tried to do this, and check. Could you go through this step-by-step? Thanks
#2 by Speedy Parker on December 15th, 2009
Quote
I will fire up my Vista and 7 VM’s and see how to check things out there. If you have Windows Vista or 7 remember you can add additional member on the fly with a USB stick by using ReadyBoost