More info added.

It's like spring cleaning. I reformatted my hard drive today and washed away two years of jumbled data. I packed up all my pics and docs and put them on a network share. We have an old computer with a 500 gig hard drive that I use for back up storage. So now my computer is like brand new. No cluttered registry, a clean msconfig start menu, no old unused programs. And the performance has literally doubled. I didn't realize my computer had slowed down so much. It has a 3.2 ghz processor, not bad for a 5 year old computer, so it should be fast. Now it is! If you have a computer that's a few years old, I highly recommend reformatting it. Make sure you save all your important files and have back up cd's for your programs such as Microsoft office. Then just reinsert your operating system CD restart the computer and go from there.

BTW if you have a laptop that is at least two years old you should completely take it apart and clean all the dust out of the fans. I've done this twice with my laptop and it's a pain in the ass but it needs to be done.