You can With MDT capture an existing Windows 7 Install.
1. Creating the Task in MDT 
Jou must Chose the OS version witch you want to capture.
2. Create a copy from the Customsettings.ini
Edit the Customsettings.ini with de following text.
[Settings]
Priority=Default
Properties=MyCustomProperty
[Default]
OSInstall=Y
SkipAppsOnUpgrade=YES
SkipCapture=NO
SkipAdminPassword=YES
SkipProductKey=YES
4. Connect to the deployement share \\server\deploymentshare$ and go to the folder script and double click on LiteTouch.vbs 
4. Don’t forget after the Capture to restore the original customsettings.ini file.