I'm sharing the internet with someone else through a router. Everything is fine except once in a while, I'd like to play games such as Quake 4 in Linux or Call of Duty 4. My ping is so horrible, it irritates me and others to play on servers. I have full access to the router, what I'd like to do is give gaming priority over all the torrent downloads going on by the other computer to cause lag and high ping with gaming servers. Is there any other solution besides unplugging his internet temporarily? I've already tried that and usually get sleepy and forget to plug it back in? Thanks for your time.

You could do that if your router has QoS on it, yes.

What type of router do you have?

It does have Qos. What should I do here?

http://img212.imageshack.us/img212/9466/qos2zx2.jpg

well you may find your apps are already listed in the drop down there, but if not you'd need to find the relevant port numbers for the good and bad traffic and manually define them. i'd peronsally be using tcpdump or wireshark on each box to see what ports are used by what. or just google it.

I am given a choice between using port ranges or mac address. It seems like the mac address way would be a lot easier, but how could the router know what application to give priority to if I use that?

It wouldn't. It would just give priority to all traffic from your NIC.