If you have a multimonitor setup and are ready to rebuild to Vista, you may want to read this first - it may cost you some $.
http://www.microsoft.com/whdc/device/display/multimonVista.mspx
Mark Miller povides even more detail here:
http://www.doitwith.net/2007/02/13/VistaI'mSoPista(partI).aspx
Does Mark now he wasn't recording a Mondays episode at the time? :)