sure you can. Every vista install dvd, eighter its a retail, upgrade or oem version, contains the same wim image that is copied to the disk, and extracted.
(by the way, an in place upgrade is actually just a clean install. Your pervious settings/documents are copied to a temp folder before the image is copied to disk and extrcated. After that, the contents of the temp folder are copied to the new intall base )
The technology that is vista version dependable, is "opened or unlocked if you will" by the key given during install.
After intallling a vista version, you can use windows anytime upgrade, to upgrade/downgrade your windows install.
