In Windows XP SP1 and above (as a result of a lawsuit) there is an easy way to set the “default” programs for certain crucial functions; to do this, go to Start -> Control Panel -> Add/Remove Programs -> Set Program Access and Defaults. Here you can set it to “Microsoft” settings, “Non-Microsoft” settings, or “Custom” (combined) settings. For example, you may want to set AIM as your default IM program but IE as your default browser.