You may perform a custom installation using a full edition of your choice of
Vista to replace your evaluation copy. You cannot use an upgrade edition to
do this since the October release was pre-release software and does not
qualify you for upgrade pricing. You may use an upgrade edition if you are
replacing the XP Pro installation with Vista but that does not sound like
your plan. You cannot use an upgrade edition based on your XP Pro to
qualify to install Vista over the evaluation copy. The upgrade edition must
install Vista over the qualifying OS.

Vista pricing is all over the web. Choose your retailer and order.

To replace the Vista Ultimate evaluation copy with something like VHP, buy a
full edition of VHP, format the Vista evaluation volume with XP Pro, and run
Vista Setup from the XP Pro desktop but select the volume that you formatted
as the target. That way your drive lettering will be the same in Vista as
XP.

While you can never "downgrade" and retain your files, settings, and apps,
you can use the Vista Windows Easy Transfer wizard to save your files and
settings to intermediate storage and restore them after the installation.
You will have to reinstall your apps.

"N5RKN" <N5RKN@discussions.microsoft.com> wrote in message
news:15A383D0-F675-4C28-A90E-43D82CC6F8AB@microsoft.com...
>I installed the full Ultimate eval version, when it was released in October
> 2006. Though it doesn't "expire" until June, I'd like to consider a
> lesser
> version. Does anyone know if I would be able to "downgrade", or would I
> have
> to do another full format and install of the lesser version (once
> purchased)?
>
> This is just 2nd computer, used for testing equipment and "show & tell".
> So, there is no issues with formatting.
>
> One other observation is that I find it hard to find actual pricing
> dependent on my "upgrade" from my licensed version of XP Pro.
>
> Thanks for any suggestions,
>
> Robert