[Al B. Drinkinbeer]

I'm not positive - but I think the only way to password your server is in dedicated mode. Someone please correct me if I'm wrong...

Have your buddies connect to your game via IP address. This way they can go straight in without having to search the in-game browser or Gamespy for it.

The All Seeing Eye is a helluva lot better than Gamespy. You can easily add servers to your favorites list, track your buddies and even issue rcon commands such as passwords, kick players, map changes, etc. to your server without your game even running. And no ads or annoying chat windows!