deselys has the easiest answer... Make a knoppix boot cd and mount the drive read-only.
You might be able to boot it and if it was set up for network file sharing, the admin share (//computername/c$/) might be shared without a password, but that's not terribly common.
I think using a linux "live" cd image is probably the easiest, followed by the various ways to trick it into giving up the login password.