because i'm tired of finding new games to play

looking for suggestions for a decent MP game to play over a LAN network with internet connection with my friends
i have 2-5 people with laptops (and a desktop for a dedicated server if necessary)
hardware isn't exactly new or powerfull, so that rules out anything that requires a 9000 GHz processor or anything like that.
usually we play RTS games and stuff like that.
sooo..... suggestions?