I've been using a free program called advanced system care lately (Iobit) and I'd recommend it to keep your computer running smoothly.
If you're a computer novice just do a regular care/scan but more computer savvy members might want to give the expert mode a go (as well as the ultra handy toolbox).
Btw go into the settings to avoid it starting at startup and the little performance console popping up.
Windows XP users might want to go to settings and move the transparency (in user interface) completely to the left in the bar for best results.
Expert mode (settings tab to the right of the little shirt icon btw):
I would uncheck disk defrag since it can take a while (maybe do that periodically when you have lots of time):
