Almost every Windows program comes with an installer and an uninstaller. Many of these installers sink their talons deep into Windows' flesh, and far too many of the uninstallers remove the program's functionality, but leave the talons. The result is a wounded operating system. Clever as it may sound, running Control Panel's Remove Programs applet just runs the unwanted program's own uninstaller. Total Uninstall ($30, 30-day free trial) does a much smarter job. Before you even start the uninstall, Total Uninstall finds the program's files and Registry keys and presents you with them. When you click the Uninstall button, it runs the program's own uninstaller, than cleans up the mess left behind. It doesn't always catch everything (the default setting errs on the side of caution, and I recommend you stay with that one), but leaves you with a healthier OS.
The $30 price tag means it costs $30 more than its popular competitor, Revo Uninstaller. But Total Uninstall can remove 64-bit programs, which Revo cannot do. It can monitor an installation and use that information to help with the uninstall months later. And it smoothly handles uninstalls that require a reboot--a task that's confusing and intimidating in Revo.
For $10 more, Total Uninstall Pro can export Registry changes, group programs into folders, run in a virtual machine, and do other tricks. (There's a $40 Pro version of Revo, too, which also supports x64 and can monitor installations, but it still can't handle reboots well.).
Total Uninstall and Revo Uninstaller each has something to recommend it. Don't uninstall anything without one of these programs.