I recently bought a shiny new home desktop machine ( 6 GB RAM, 1 TB Hard Drive) to act like a server at my house.  I installed W2k8 R2 Enterprise, added Hyper-V role.  My goal was to be able to create VM’s for testing ‘stuff’.  I wanted to create one base image, sysprep and make copies when I wanted more machines quickly.  I’ve used VPC 2007 to create one image and copy / paste the VMC and VHD files.  Hyper-V is not quite that simple (yet).  Here are the steps I used.

• Install w2k8 r2 on the host machine
• Add Hyper V role
• Create a new VM to act as the base IMAGE
• Mount an ISO version of your favorite OS (windows 2008 or R2)
• Load the OS
• Run Sysprep (/generalize switch enabled), Shutdown
• Inside Hyper V manager, Export to a alternate location
• After Export is done, copy the entire folder to your permanent location
• Inside Hyper V manager, import the VM you copied.
• Rename to a friendly name.
• Fire the new VM up, run through the sysprep process and poof!
• Make sure you chose “Copy the virtual machine (create a new unique ID)’ option, this is not the default.

Another tip / trick I did on my base image (first VM) I created was after I was done, I renamed the image in Hyper V manager, because when you import, the name is retained when exporting.  This helps preventing the same name VM listed in Hyper V manager. 

Here is a good article that helped me figure out using export option.

http://www.virtualizationadmin.com/articles-tutorials/general-virtualization-articles/cloning-hyper-v-virtual-machines-right-way-part4.html