Will a motorola sb5100 surfboard cable modem work with a router, so i can sign

[ShadowBlade77]

up for ps3 network? I have a motorola sb5100 surfboard cable modem and it only has one Ethernet cable slot which is already plugged into my computer. how do I connect my modem to a router so I can play my ps3 online? The other plugs that it has is a cable plug in which is already plugged in and a power cable that is connected to an outlet. The only plug that isn't connected with anything is the usb plug in.

Any ideas

Here is a picture of the modem
http://mosaic.cnfolio.com/uploads/M528Coursework2008A101/motorola_sb5100.gif