Microsoft has release new tool called Sysprep which can prepare any windows for cloning giving Out Of the Box Experience (oobe) .
The tool locate at : C:\Windows\System32\Sysprep/pre>
double click on the sysprep.exe
Checkbox generalize checkbox. If you intend to transfer a Windows image to a different computer
For VM you can run from command line :
sysprep.exe /oobe /generalize /shutdown /mode:vm
This will boost the performance and time for the virtual machine for the first startup and installation. This work of course with virtual machines running on any hypervisors such as Hyper-V VMware or Xen.