When selecting a Microsoft Intellimouse (Serial) as my mouse, the X
Installer automatically chooses default actions for the next 4-5 screens
which include type of install (Workstation default, I wanted upgrade),
Automatically partitioning and formatting (um, no), time zone, and a couple
other minor screens.  The next screen you get to choose anything at is the
root password prompt and by this time the installer has blown away your
existing partitions.  This problem does not present itself if you choose a
standard 2 button serial mouse.