It's possible to deploy an OS image without formatting the hard drive, and leaving user files intact. It does uninstall all apps, but user data and state information are retained. In this method, one starts the Deployment wizard from the MDT Server's Deployment share from within the existing Operating system.
1. Boot to the existing OS as an Administrator:
2. Connect to the MDT Deployment Share: Click on the start button and type \\ltsmdt002.cc.lehigh.edu\MDTProduction$ and press 'Return'. Then, supply your Lehigh credentials with "ad\" preceding your username.
3. Run the Lite-Touch Deployment Script: Navigate to the LiteTouch.vbs script in the Scripts folder (\\ltsmdt002.cc.lehigh.edu\MDTProduction$\Scripts\LiteTouch.vbs). Double-click to run it, and calm any security warnings about running scripts.
4. Log into the MDT system with your Lehigh credentials.
6. The next screen allows the choice of image you'd like to deploy.
Be kind, and don't deploy images (and software licenses) for departments you don't work for. Choosing your image may depend on which machine model you're working on -- some machines have multiple drives, and require them to be deployed in a certain layout.
Click the radio button next to the 'task sequence' you'd like to run (the image you'd like to deploy), and click 'Next'.
7. In the last screen, simply make sure that no errors are indicated (i.e. that a machine name like 'FS<this machine's MAC address> has been automatically entered correctly), and click 'Next'
8. Skip taking a backup, since there's no place to put it, and click 'Next'.
While the deployment runs, there will be progress bars . . .
9. The deployment should finish in the local 'Administrator' account, with an indication of success (yellow screen).