An update to my previous post regarding failed installations of Visual Studio 2008 RTM when a Beta or RC version was previously installed....
ScottGu posted a complete list of products to uninstall before launching the VS 2008 RTM setup:
http://weblogs.asp.net/scottgu/archive/2007/11/20/steps-to-uninstall-vs-2008-beta2-before-installing-the-vs-2008-final-release.aspx