yep its true. Applicable only for Business, Enterprise and Ultimate users only
Edit: From Vista Ultimate EULA
USE WITH VIRTUALIZATION TECHNOLOGIES. You may use the software installed on the
licensed device within a virtual (or otherwise emulated) hardware system on the licensed device. If you do so, you may not play or access content or use applications protected by any Microsoft digital, information or enterprise rights management technology or other Microsoft rights management services or use BitLocker. We advise against playing or accessing content or using applications protected by other digital, information or enterprise rights management technology or other rights management services or using full volume disk drive encryption.