Uninstalling SharePoint 2003

I installed SharePoint 2003. It was working until I unistalled something wrong. Now I can't uninstall the program or repair it or reinstall it without it erroring out. I even went into the registry and got rid of the entries for SharePoint. It still sees a piece of the program and won't reinstall. You can't do it through Add and Remove programs either because it errors out and that is part of Microsoft's idea of manually unistalling the program. ( Not too manual) Anybody help??? It's installed with SQl 2000 which is running fine. Help!!!