This isn't just SharePoint but just general server/pc help.
Way to often people call/email/IM me about problems uninstalling software, usually after the uninstaller crapped out half way through the process or they hit cancel because it was taking too long to run. Or the reverse of that the install went belly up. They then end up in some limbo state of the software is only kind of there and they can't remove it. Well my first advice is format the box but, nobody likes that. So the second piece of advice is to run the Windows Installer CleanUp Utility. http://support.microsoft.com/kb/290301 This awesome little tool will show you everything that has been installed by the Windows installer and will allow you to remove any of those files. Not the actual program but all of the behind the scenes files that make the install possible. With those out of the way you can typically rerun your installer/uninstaller and do the job right.
I know when alpha/beta testing Office and SharePoint in the past this tool was a must.
Shane – SharePoint Consulting