Some people have asked me and I've also seen this question in the MSDN installation forums (Visual Studio 2010 Install and Setup):

Q: What's the setup experience if I have a pre-release version of VS on my machine and I'd like to upgrade to the newest released version?

Answer: You will need to go through the uninstall of the VS pre-release version and then install the newest VS version. The installation of the newest version will show up a block message on the pre-release version of components that are installed on your system and need to be uninstalled in order to get the newer bits.