Virtual Hard Disk (.VHD) files are used by Virtual PC and Virtual Server, and created by Windows Backup when you make a system image backup. If you ever need to access files contained within a .VHD, you can do it using the Disk Management tool built into Windows 7. Just follow these steps:
1. Click Start, right-click Computer, and then click Manage.
2. Expand Storage, and then click Disk Management.
3. Click the Action menu, and then click Attach VHD.
4. Click the Browse button, select your VHD file, and then click OK twice.
5. Open Explorer and access the VHD like a newly created hard disk. It’ll show up as a blue disk in the Disk Management snap-in. For example, mine appeared as the H: drive.
ref: http://www.vistaclues.com/open-a-vhd-file-in-windows-7/
