This night , i deployed a native VHD boot On win7 for windows server 2008 R2. It is a new feature supporting VHD boot on win7 for VHDs of  windowser server 2008 r2 and win7 enterprise version . The precedure is simple:
   1. Gernerate a VHD by hyper-v ,virtual server or other script or GUI method.
    2.After a brand windows server 2008 R2 or WIN7 enterpise version was deployed in VHD, it have to be syspreped.
    3. make a boot item in boot loader of win7 , to let user can select which OS should be startup
     For my practice , i got a WINDOWS server 2008 R2 VHD from new virtual machine powered by Hyper-V. and compacted the virtual disk then implement sysprep .
    next step , i copied the VHD to a destination folder , in the meanwhile i made the other copy for the vhd to act as a parent vhd for a certain difference disk deployment to save disk resource for some lab in the future.
   ok, all these steps finished. Boot  Menu should be modified according real deployment. In the practice, i copied VHD to D:\VHD\WIN2K8r2.VHD
* Creat a boot item name for VHD-boot
    bcdedit /copy {current} /d "win2008R2-VHD"    -----The command line means that i will create a item name win2008R2-VHD for boot selction in the boot menu
 (please note the associated GUID of the item it will  present after command running successfully , and copy the GUID for following task)
* point the destination VHD for the boot item
  bcdedit /set  {guid} device vhd=[d:]\vhd\win2k8r2.vhd
  bcdedit /set  {guid} osdevice vhd=[d:]\vhd\win2k8r2.vhd
      Once all these precedures were done, Reboot is needed  and try to select the new boot item for VHD boot to test whether it works.
The details about benifit and deployment of the native vhd boot solution can be found at MS teachnet ----