KCleaner

KCleaner will search for and delete the most common types of unnecessary files, like your browser cache, the contents of your recycle bin, and your temporary files. But it also hunts down many of the files that third-party applications--like Google Earth, QuickTime, Firefox, and even Google's new Chrome browser--leave behind.

The interface is very basic--it lacks the polished appearance of also-free rival CCleaner, for example--but it's easy to use and configure. You can select which types of files to include and whether (and how) to secure the files that KCleaner deletes. It found almost 1GB of files to delete on my sluggish PC--which seemed to run quicker after I ran the app.

KCleaner lacks some of the extras you'll find on CCleaner; it doesn't have a specific registry cleaner or the ability to control which applications load on your PC at startup, for example. But it does include an automatic mode, which you can set to run in the background (you choose the frequency) to make sure your newly-cleaned PC stays that way.

Newbies may be intimidated by KCleaner's very sparse interface (and the absence of much guidance from the app itself), but they should also appreciate the fact that it lacks some of the bells and whistles that have the potential to damage your PC.

--Liane Cassavoy