Lest your local geeks-for-hire take you for a ride (or fleece someone you love), we've rounded up a representative sampling of typical repair-shop services to help you sort the rip-offs from the reasonable deals.

In this article, I'll explore some of the most common offerings you'll find at repair shops large and small. These aren't scams, to be sure--as far as we know, these are all legitimate services from legitimate businesses. But the actual value of these services--relative to the work involved and the likely benefit to the consumer--can be highly questionable in many cases.

Just about every repair shop I've encountered offers some kind of "tune-up" service that promises to improve your PC's performance by deleting temporary files, defragmenting your hard drive, removing unused applications, running Windows Update, and (in many cases) cleaning the Windows Registry. These services often cost $50 to $100, but generally they don't do anything useful that you couldn't do yourself with a free download and some utilities that come with your PC.

Before you shell out a hundred bucks, think about what this service entails: Windows comes with a utility called Disk Cleanup that will delete temporary files for you with a few measly mouse clicks. Disk Defragmenter--another built-in Windows tool--typically runs automatically on a weekly basis, but you can launch it yourself by going to Accessories, Utilities and clicking Defragment Disk. Windows Update also runs automatically by default, but you can click Start, type Windows Update in the search field, and run it yourself on command.