Deploying VMs from templates harks back to the bad old days of disk imaging.  But using “baremetal templates” ensures your virtual hardware configuration is consistent (choice of NIC, choice of array controller, disk is thin provisioned etc..).  Then make a baremetal template that boots straight into WinPE for unattended OS deployment. Then you get consistent VM hardware config without maintaining a distributing OS disk images.

Create VM template or factory image with WinPE on harddisk

Create VM with required virtual hardware configuration

1. Boot from MDT/WinPE ISO,
2. partition disk,
3. copy D: to C: (D is the win WinPE ISO)
4. shutdown
5. Disconnect ISO
6. capture VM to template

F8 from WinPE to get command prompt. Prepare VM system disk so it boots into WinPE:

diskpart
select disk 0
clean
create partition primary size=2000
select partition 1
assign
active
format
exit
robocopy d:\ c:\ mir
wpeutil shutdown

• Makes small 2GB partition for winPE for faster cloning. Partition will be blown away during MDT build process.
• Remove CD from VM hardware settings. You won’t need this for deployed VMs.
• Then convert this VM to a VM template (admin rights in virtual center required)

Ref:http://technet.microsoft.com/en-us/library/cc766195(v=ws.10).aspx