Here's one method you can use for updating a Windows image that you want to deploy using MDT 2010:
1. Deploy the image onto a computer
2. Then use WUAUCLT /detectnow to update the image.
3. Then use the Sysprep and Capture task sequence to sysprep the computer and capture its image.
Note that this works even if the image you deployed is domain-joined since Sysprep automatically removes the computer from the domain when it is run.