Not true.
Vista 32 and 64 bit come on separate DVDs. If you buy Vista Ultimate both are in the box, just install the one you want. Other retail boxes and OEM disks are sold just in the 32 bit edition. If you want the 64 bit you go to the MS site and order it, entering the 32 bit version serial number. MS then cancel the authorisation for that copy and post you out the 64 bit DVD. They charge a nominal amount for P&P - see
here..