Dell Vista Update 64 Bit Enabled?

Does anyone have word about the 64-bit capabilities of the Vista Update disks? I read from http://www.windows-vista-update.com/Windows_Vista_64_bit.html that 32 and 64 bit versions are on the same DVD. However, the wording on Dell's own site
http://www.dell.com/content/topics/global.aspx/solutions/en/vista_express_upgrade?c=us&l=en&s=gen
makes a distinction between Vista Business and Vista Business x64, implying that XP Professional (not x64) will qualify for a 32-bit upgrade only.

Which one is right? Microsoft wouldn't give out different disks for retail (which according to the first link is both 32 and 64 on the same disk) and upgrade (which according to Dell is implied to be 32 only), would they?

Please answer if you have any knowledge of this situation
Thanks

 

unless its a really odd oem customization Dell is doing....all vista CD's are pretty much whole in 32 ansd 64 bit versions on one disk. In fact, the basic version and the ultimate version (at least in retail) install from the same disc, just the key dictating the installed featureset.

 

I don't think both are on the same DVD unless they are putting them on dual layer DVDs. While beta testing vista, the 32 bit version just barely fit on a single layer DVD. To install the later versions of the 64 bit required a dual layer DVD.

 

the rtm releases are on one DVD, they really trimmed the fat.

From the beta2 build to the RC2 build, the 32bit build was trimmed 1gb. I can also imagine how much of the info on the 32bit and 64bit discs are the same.