Can I install Vista 32-bit edition on one computer, and Vista 64-bit edition on
another?
Windows Vista includes both a 32-bit installation DVD and a 64-bit installation
DVD.
However, you may only install one or the other. Even though two
DVD's are included, you may only have one copy of Windows Vista installed at a time.
If you upgrade your computer from a 32-bit computer to a 64-bit computer, then you
may REPLACE your copy of Vista 32-bit with Vista 64-bit; however, you must never
have more than one copy of Windows Vista installed at the same time, unless you
purchase another copy of Windows Vista.