1. Speed up a sluggish PC
Computers slow down over time - that's normal. If your PC is fairly new and it's slow, remove the pre-installed programs, or bloatware, that came with it. PC Decrapifier will remove trial programs and other junk in a snap.
To give an older PC a speed boost, break out the CCleaner. This tool looks through Windows, Web browsers and other third-party programs for unwanted clutter and gets rid of it. CCleaner can also scan and fix errors in Windows' registry. Just make sure you allow it to backup the registry before making changes.
Grab Duplicate Cleaner to remove duplicate files that might be clogging up the system. But, limit your file hunt to the Documents area of your computer. You don't want to accidentally delete important system files.