Age of Empires 2... AOE3 might work too, but I dunno if you can play LAN, and it may not work on your friend's system if it's too old. My HP notebook doesn't handle the AOE3 trial too well... I like AOE2 for playing LAN mutiplayer. We played it over the school network when there was a bunch of downtime in class.
Halo is about the only fps game I will play mutiplayer.