Windstream modem disconnects my Windstream 2wire router?

I play COD online but i lag all the time when someone is on the computer. (Im using a wireless 2wire modem). So i thought if i got a windstream 4200 modem to hook up directly to my ps3 it would make my connection better whether or not someone is on the computer. But when i hook up my modem, my router gets disconnected to the internet? Any help?|||This is because you are trying to connect two DSL modems to the same phone line, and you can only have one DSL modem per phone line. My suggestion would be to use the 4200 and a wireless router instead of a 2wire that does both.