Out, out, @#!% spot! The days of simply deleting a folder to uninstall a program are gone with the winds of DOS. Modern programs insinuate themselves into every nook and cranny of Windows, and the built-in uninstaller doesn't always find all the remnants. To do a completely thorough job, use one of these uninstallers instead.

This is particularly important when changing anti-virus horses as remants from a competing product can cause troubles for a different product. Virtually every anti-virus developer has available an additional removal tool for this very purpose. Simply Google to find the most current link, e.g. "McAfee Removal Tool".

Cleanup

Revo Uninstaller - finds all the stuff Windows uninstaller misses: registry entries, folders, etc.

Iobit Uninstaller - fully uninstalls programs, including toolbars