For you benefit and amusement: here is my experience with upgrading to Visual Studio 2010 Service Pack 1.
10 minutes later:
Another 25 minutes later:
NOTE: If you are working on a Word document while installing the Visual Studio Tools for Office then be warned that the installer will automatically shutdown Word when it reaches this step! I lost a bunch of changes because of this! 
Restart required:
Reboot complete… start Visual Studio 2010 and check the Help | Info screen:
Life is good!
I’ve checked my DevExpress add-in and also the Code Contracts add-in that I’ve got installed and both seem to be working fine. Nice!