If the computer does not have anything on it, I would just go ahead and do a system restore either using your restore CDs if you have them or using the systems recovery partition if it's a newer computer. I wrote a little about doing a system restore using the restore partition here:
www.kmctechguy.com/forums/general/70-res...uter-without-cd.html
If after doing a clean install, your system still seems like it is running slow, it most likely indicates that you have a hardware problem. You can read more about some issues I posted that may be causing you to have a slow computer here:
http://www.kmctechguy.com/forums/general/50-slow-computer.html
If you do have a hardware problem, it could be a memory issue, CPU, or hard drive. To test your memory, there is a great free program called mem86. You can read about it on their website
http://www.memtest86.com/.
If this is too confusing or if you still think you need help, I can always come by and do on site support or you can drop the computer off at my place. Let me know how it goes. Hope this info helps.