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Upgrade versions of Windows Vista Home Basic, Premium, and Starter Edition will not install on any PC unless Windows XP or Windows 2000 is already on the machine in question. In years previous, upgrade versions of Windows could be installed on any PC. If a PC did not have an older version of Windows installed, users could provide an older installation CD of Windows for verification. After dropping a qualifying CD in the CD-ROM drive, the installation routine would verify the disc and you'd be on your way. With this approach, one could use an "upgrade" copy of Windows to lay a new Windows install on a computer.

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For its part, Microsoft seems to be confident that the Vista repair process should be sufficient to solve any problems with the OS, since otherwise the only option for disaster recovery in the absence of backups would be to wipe a machine, install XP, and then upgrade to Vista. This will certainly make disaster recovery a more irritating experience.

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According to Microsoft, only the full retail license of Windows Vista can be transferred to new devices (retail pricing here). OEM versions are ostensibly tied to motherboards, and upgrade versions are now technically tied to previous installations.
Get ready to fork it over, Daddy Balmer's stock price is too low for his liking.