One of my clients has taken his computer away from the windows domain to another office. He has now forgotten the password to his account. I told him he needed to bring the computer back to the domain for me to reset, it but he didn't like that suggestion at all.
Is there any other way to reset his password?
Sometimes you can use dial-up networking from the windows login screen to connect to a VPN to do the authentication. Not sure if the VPN needs to have been already set up, but if you log in as local admin you should be able to set it up "for all users" and then connect to the remote network from the login screen. I've done it with a Windows 7 client.
For a Free & Open Source tool, try chntpw/ntpasswd - bootable CD/USB/floppy images available. Be aware that most virus scanners will warn you about the included tools, though.