Hello, here are just a few suggestions on how to speed up your PC and free up space.

- Run Disk Defrag - Go to Start > All Programs > Accessories > System Tools > Disk Defrag
- Run Disk Cleanup - Go to Start > All Programs > Accessories > System Tools > Disk Cleanup
- Eliminate unneeded programs on startup - How to Alter Startup Programs in Windows XP - wikiHow
- Upgrade your RAM - Memory upgrades from Crucial.com - About Crucial:Media Toolbox
If your computer is running unusually slow (or if you just want to be on the safe side and make sure), please follow the prework link in my signature to make sure you don't have any malware on your system.
As to PerfectDisk 2008-- I personally think that the Windows Disk Defrag works just as well. Others may have different opinions, but I wouldn't pay 39.95 for it.
Regards,
Adam