(Image credit: Apartment Therapy )
Here's a helpful, if not amusing, chart from Lifehacker illustrating a variety of maintenance practices for Windows users, categorizing them according to their perceived value opposed to their actual helpful (or harmful) utility. Seems good, but is really bad, seems bad, but is actually good, or just downright bad...

Read Windows Maintenance Tips: The Good, Bad, and Useless at Lifehacker.