There are no servers for Netmeeting anymore since they switched to MSN. You can connect directly to him via his IP address or hostname, provided you have opened the appropriate ports in your firewall.
I've tried it (Netmeeting and Gnomemeeting) but the netmeeting could not see the video being sent from gnomemeeting. Sound did work. Gnomemeeting did see the video from netmeeting. Of course, that was a while ago, and might be more functional now.
You might give a whirl to a fork of Gaim called gaim-vv
, which will be eventually backported into the main Gaim CVS. It supports video and voice, and works in both Windows and Linux.