*copied and pasted from email*
Important Information about Windows Vista RC1 . We remind you that RC1 is
pre-release software and you should not run this on production or
mission-critical PCs. Support will be limited to newsgroups, and you may have
to do a clean install to move from this release to the final release of
Windows Vista.
.. You may upgrade an existing installation of Windows Vista Beta 2 or
Windows XP to this release. However you will have to do a clean install if
you want to get back to a previous configuration.
.. Before upgrading from Beta 2 to RC1, please install any Critical Updates
from Windows Update for Beta 2. Go to Start, All Programs, Windows Update,
and click the "Check for Updates" button.