This video goes over how to create a forensic image using the Windows command line with the dd tool.
For more information on dd and how to download it visit http://www.chrysocome.net/dd
CAUTION: dd is a powerful command line tool that can erase ALL of your data. Please make sure you are using the tool properly before executing any commands. If able, test the tool in a Virtual Machine (VM) environment to avoid permanent damage to your host machine.