Second broadband router?

IN my house i have 3 pcs and 1 laptop. I have a broadband router from cablevision. Connected to my linksys router. Im up stairs thats down stairs. My signal strength is really low and i recently got a hava which records xbox 360 gameplay to my pc. The probelm the hava streams extremely slow due to low strength signal. Im wondering if there is a way to hook up a second line of the black cablevision router.

All my pcs are connected WIRELESS