I am hitting them as I go along - here is another tip that is very useful.
A .MSI-file cannot be executed under another account then the one you’re running with. There is no “Run as…” in the right-click menu for .MSI-file, in other words.
Here is the solution for Vista which works very good on XP also (I’ve tried). It is a reg-file that simply adds the “Run as …“-feature when right clicking .MSI-files