Apparently it is possible to downgrade from OEM Vista to XP. I know that many people prefer XP over Vista, so it would be great to hear if anybody succeeds in getting the downgrade.
Downgrade your Vista to XP
Ever since Vista machines have been popping up in stores, we have had users perpetually asking how they can downgrade their Vista machines back to Windows XP. For some brands like Dell, consumers can choose at the point of sale to preinstall XP. For others, they have had to buy an XP license while hunting for the proper drivers.
According to a recent News.com article, there are some in the second group may have wasted their money. Turns out that if one had actually read the license terms--which we dare say 99 percent of users don't--OEM versions of Vista Business and Ultimate Editions can be downgraded to XP without additional cost.
When contacted, Microsoft told CNET Asia that owners of these versions need only call the customer support center, cite the Vista serial number and get an activation code for Windows XP Professional, XP Professional x64 or XP Tablet PC Edition. So even if the notebook does not come bundled with an XP CD, you can use an older disc from a previous machine and put in the new activation code. Vendors who buy into this program will bundle their system with both Windows XP and Vista recovery discs.
When contacted, Dell mentioned that it already has this program in place for its Asia consumers, while ASUS and Toshiba will be participating in this program at a later date.
[Edited at 2007-09-26 01:44]