There have been a few questions about how to correctly uninstall all of VS 2008 Beta 2 in order to install the final version of VS 2008. Scott Guthrie posted the steps for doing this earlier today. A subset of this list would apply if you have installed Team Foundation Team Explorer 2008 Beta 2, rather than the full VS 2008 with Team Explorer.
At the end he recommends rebooting after removing everything and before installing VS 2008. From my experience, that's good advice. The only thing additionally I've typically done after uninstalling a non-RTM build is to delete the VS 9.0 registry hives (HKLM and HKCU) and the VS 9.0 directory under "Program Files." Of course, there are no guarantees with this, editing the registry may render your machine nonfunctional, etc., so be careful and back up your data.
A few people have pointed out to me that there are other smaller setup packages that are optionally installed by Visual Studio 2008 Beta2 that you should also look to uninstall (it isn't always required to-do this - but it is best to always do this to be safe). A complete list of these additional setup packages (along with uninstall instructions) can be found here.
Below is the complete list of potential Beta2 components to uninstall (as well as the recommended uninstall order of them):
Remove "MSDN Library for Visual Studio 2008 Beta" Remove "Microsoft SQL Server Compact Edition 3.5" Remove "Microsoft SQL Server Compact Edition 3.5 Design Tools" Remove "Microsoft SQL Server Compact Edition 3.5 for Devices" Remove "Microsoft Visual Studio Performance Collection Tools" Remove "Windows Mobile 5.0 SDK R2 for Pocket PC" Remove "Windows Mobile 5.0 SDK R2 for Smartphone" Remove "Crystal Reports 2007" Remove "Visual Studio Asset System" Remove "Microsoft Visual Studio Web Authoring Component / Microsoft Web Designer Tools" Remove "Microsoft Visual Studio 2005 Tools for the 2007 Microsoft Office System Runtime" Remove "Microsoft Visual Studio 2005 Tools for the 2007 Microsoft Office System Runtime Language Pack" (non-English editions only) Remove "Microsoft Visual Studio Tools for Office Runtime 3.0" Remove "Microsoft Document Explorer" Remove "Microsoft Document Explorer 2005 Language Pack" (non-English editions only) Remove "Microsoft Device Emulator 3.0" Remove "Microsoft .NET Compact Framework 3.5" Remove "Microsoft .NET Compact Framework 2.0 SP1" Remove ".NET Framework 2.0 SDK" Remove "Microsoft Visual Studio Codename Orcas Remote Debugger" Remove "Microsoft Visual Studio 64bit Prerequisites Beta" (64-bit platforms only) Remove "Microsoft .NET Framework 3.5"
After you finish uninstalling any and all of the above items, I'd recommend rebooting prior to installing the final VS 2008 and .NET 3.5 release to make sure there is no setup state still on the machine.
If you run into any problems with either installation or uninstall, please make sure to post in the Visual Studio 2008 Setup and Installation Forum on MSDN.