Slow computer performance can be caused by a number of things, not just spyware or viruses. The number one way we’ve found to speed up a computer is to increase the amount of available memory — if you’ve loaded a number of programs onto that computer over the years, and there have been a number of items added to your startup files, it may be the the RAM you have in that system simply isn’t enough to comfortably handle what your computer is running in memory at all times. The easiest way to pep things up is to add RAM to your system — with memory so cheap there’s probably very little reason not to pump your system up to 1 GB of memory if your system can handle it. If you can’t upgrade your ram for whatever reason, try removing items from your startup folder. You can do that using Microsoft’s built-in msconfig utility (type “msconfig” into the Run window from the Start menu), or if you want more control, try downloading SysInternals’ AutoRuns program, which is like a turbocharged version of msconfig: http://www.microsoft.com/technet/sysinternals/utilities/autoruns.mspx

If you really want to pep up your computer though, the best way is to format your drive and reinstall Windows from scratch, then only reinstalling the programs you need.