Most people know a desktop PC needs cleaning now and then. The usual advice is physical: Open the case, clear out the dust, check the fans. Weve covered that in our guide to cleaning and organizing your Windows PC . But there a second chore that gets far less attention: the junk piling up inside Windows itself. Microsoft ships a few tools for it, and we wanted to know how well they work, so we ran a scan only test of each on the same drive. Nothing was cleaned, and nothing was deleted. What...