XP Quick Fix Plus is a tiny portable application that presents 40 quick fixes arranged in a push-button chart. Press the button for the problem you're having like CDs not autoplaying, file associations greyed out, the boot.ini tab missing in MSCONFIG, or any of the other 40 common problems, and XP Quick Fix Plus will patch the registry key for the problem you're having and get things back in working order.
Not sure if the button covers the problem you're having? Mousing over the buttons gives you a detailed description of the problem. Have a favourite quick-fix tool to share? Let's hear about it in the comments. XP Quick Fix Plus is freeware, Windows only.