So long as you have a product key for 'both' the 32 bit and 64 bit versions
(you can't install both 32 bit and 64 bit using the same product key number)
then it can be done. See this link from my website:
http://vistasupport.mvps.org/install_windows_xp_on_machine_running_vista.htm
Vista creates its own boot menu so when you boot your machine you will be
give the option to boot into either the 32 bit or 64 bit operating systems.
Incidentally, as you would be installing two versions of Vista, the names on
the boot menu would be the same. After installing your dual boot system
download VistaBootPro (
www.vistabootpro.org) a user friendly application
that will enable you to edit the boot menu and rename the operating systems
on the boot menu so you know which one you are opening.
--
--
John Barnett MVP
Associate Expert
Windows Desktop Experience
Web:
http://xphelpandsupport.mvps.org
Web:
http://vistasupport.mvps.org
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