mhh..let me think...I've got a brother so we have play a lot of them...
A nice game is Re-Volt (I don't know the status but it's really funny for a child)
Another one...if I'm not wrong Gta support lan games and you can easily find it on abandonia reloaded!
You can try Wolfenstein Enemy territory (freeware), but it could be too boring with only two players...
If I'll remember other titles I'm gonna tell you!
k: