Yes, Vista will install. If you do not enter a PK and choose to proceed you
will get a menu offering Home Basic, Home Premium, Business, and Ultimate.
You would then have 30 days to evaluate the product. If you then later
tried to enter an upgrade pk it wouldn't work because not entering a pk in
the beginning results in a full edition installation. However, you could
enter a full edition pk within the 30 days that corresponded to the edition
you installed in the event you had decided to go that route.

A product key is bitness agnostic. The same key works for x86 and x64.
What the key determines is the license. It determines whether you are
installing a volume license, upgrade, or full edition and whether it is Home
Basic, Home Premium, Business, Enterprise, or Ultimate. Setup branches to
the installation routine "unlocked" by your pk.

Bitness is not an issue because you cannot upgrade from x86 to x64 anyway.
In fact, the only users that can take advantage of a Vista x64 Upgrade Setup
are those already running XP Pro x64.

"Brian W" <brian.NOSPAMwescombe@PLEASEntlworld.com> wrote in message
news:5gkfh.5433$Dr3.1941@newsfe2-gui.ntli.net...
>
> "Colin Barnhorst" <colinbarharst@msn.com> wrote in message
> news:E6D1F8A8-CD1A-4437-9208-D66B8C55C580@microsoft.com...
>>
>> An upgrade dvd will boot the system. However when you type in the
>> upgrade product key you will be prompted to reboot and run Setup from
>> your legacy system desktop.
> I have wondered what would happen if you booted from an Upgrade disc but
> didn't enter a product key. Would Vista install? Assuming it would, what
> would happen when an (upgrade) key is then entered? This question applies
> to both 32 and 64-bit versions
>
>