A few things that I’ve run across in the last few days…
1) If you have both TFS and Team Explorer installed on the same server, you may not upgrade just one of them to the SP1 Beta, you would need to upgrade both of them if you want to upgrade either of them. If they are on different machines, there is not a problem.
2) When installing Visual Studio 2008 SP1 Beta on top of Visual Studio 2008, VS user settings are reset to default VS settings. This bug is caused by code originally put in place to reset settings when upgrading minor version of VS, for example from VS Beta1 to VS Beta2 so that VS would have the latest default profile settings. VS does migrate settings from VS 2005 to VS 2008. VS certainly should keep user settings when upgrading to a service pack, which will be fixed for SP1.
Please backup your VS settings before upgrading to VS 2008 SP1 Beta.
Before installing SP1 Beta1, use the “Export Settings” wizard (“Tools” menu, “Import and Export Settings…”) to save your current settings, then install SP1 Beta1, and then use the wizard to import your settings back into VS.