Viewing webcam over a network

I have a desktop computer upstairs and a laptop with a wireless connection. I have them networked together so they can share the printer and some of the folders. The upstairs computer has a webcam installed.

What would be the easiest way for me to be able to view the webcam on the laptop? Do I need more software or is there something built into Windows? Both computers are running XP.

Netmeeting or Windows Messenger could probably do that. Both computers probably already have 'em.