I have updated the following MZ-Tools Series articles to fix/explain better some things, provide C# code some cases, cover Windows Vista folders, cover Visual Studio 2008/2010 in some other cases, etc:

HOWTO: Removing commands and UI elements during Visual Studio .NET add-in uninstallation
http://www.mztools.com/Articles/2005/MZ2005002.aspx

HOWTO: Reset a Visual Studio add-in
http://www.mztools.com/Articles/2006/MZ2006014.aspx

HOWTO: Get rid of a Visual Studio add-in
http://www.mztools.com/Articles/2006/MZ2006018.aspx

INFO: Visual Studio .NET Add-In Commands Disappear On Next Session
http://www.mztools.com/Articles/2005/MZ2005014.aspx