I was recently trying to save a bit of disk space and I noticed that it is possible to uninstall various previously used MapSource Maps (which often consume a gigabyte or two of space) even if you are running an 'upgrade' version of MapSource.
On my system I had City Select version 6, City Navigator v9 an City Navigator 2008 Upgrade. So I used the windows control panel to uninstall City Select v6 and CN v9.
Just saved about 3GB of space!
MapSource with CN 2008 still works fine.