Free File Wiper is a simple tool which helps you securely delete confidential files so that they can't be recovered later.
You've probably seen plenty of programs which promise the same, but Free File Wiper is unusually easy to use. There's no bulky interface to explore, at least not initially, just a trash can icon which floats on your desktop; drag and drop files onto this and they'll be despatched forever. (And this really is "forever", there's no chance of recovery here, so be very careful when choosing the files to destroy.)
If you need more control, right-click the icon for additional options. The most useful is the "Wipe Method", which defines exactly how your files will be destroyed. Methods range from deleting and overwriting with zeros, to deleting and overwriting seven times with a combination of zeroes, ones and random characters. The process is fairly swift, although the greater the number of overwrites, the longer things take.
Please note, the program will by default install browser toolbars. Pay special attention during the setup process and click "Skip" or clear the checkboxes next to anything you don't want.