I just read a great post on MSDN blogs regarding vhdmount, a tool in Virtual Server 2005 R2 SP1 Beta 2 (that's a seriously long name) that allows you to mount VHD files to the host operating system, and with the registry changes in this write-up you can associate the executable with the file type so when you double-click on a .vhd file it will automount. Sweet!
So why does this matter to Windows client? Because in Vista, Windows Backup creates .vhd files when a full backup is performed. That's right, you can snapshot your machine, online, and it will create a VHD for you. You can test it yourself through the GUI or using the command line tool wbadmin. This is not a P2V tool. You cannot boot to the VHD, however I've been told you can mount the .vhd file on a virtual machine as a data volume if you need to extract just certain files. Well, this is just too cool not to try, so I gave it a shot this morning.
First, I ran a backup. I ran this completely online, while doing research and listening to streaming music. In Vista, Windows Backup leverages Volume Shadow Copy Service (VSS) so you don't need to use offline tools to backup your OS volume. I captured 11 GB in around 15 minutes, give or take, to my external HDD. I plan to post again later about wbadmin, it's a great tool.
Next, I downloaded and installed Virtual Server 2005 R2 SP1 Beta 2 from Connect. I found the vhdmount tool in c:\program files\Microsoft Virtual Server\Vhdmount. I executed vhdmount with a /p and pointed to the VHD file on my external. Success! The .vhd file mounted up like a charm and I have full read/write access!