As can be seen from this dialog, Virtual PC 2007 can support connectivity of a VM to as many as three separate virtual hard drives (shown here, only one is being used). This independence of storage and VM makes for some interesting possibilities. For example, let's say you have two VMs that have different reasons for accessing the same data at different times. Well, if that data is storied in a virtual hard drive (VHD), you can point multiple VMs to it as a though it were those VMs' second hard drive (not simultaneously).
Or, let's say you needed to distribute data in a batch mode.Some master system could update the data stored in a VHD, and then the VHD could be distributed the way any other data file might get distributed (FTP, CD-ROM, in some download directory, etc) and then each user (assuming they're running with Virtual PC) could simply over-write their existing data VHD with the new one. The possibilities are very interesting the minute you move to a virtual machine model.
For David Berlind's write-up on The Virtual PC 2007 User Interface, see his post
in ZDNet's TestBed blog.