From the aforementioned page:
The password to login to all of these images is Password1 and the username will be present when you first login.
*Note: You may be required to activate the OS as the product key has been deactivated. This is the expected behavior. The VHDs will not pass genuine validation. Immediately after you start the Windows 7 or Windows Vista images they will request to be activated. You can cancel the request and it will login to the desktop. You can activate up to two “rearms” (type slmgr –rearm at the command prompt) which will extend the trial for another 30 days each time OR simply shutdown the VPC image and discard the changes you’ve made from undo disks to reset the image back to its initial state. By doing either of these methods, you can technically have a base image which never expires although you will never be able to permanently save any changes on these images for longer than 90 days.