How can i get my 20MB speeds through my wireless router?

Hello, I have just been upgraded to 20MB internet speed by Virgin Media. My question is this: I have 2 computers and 1 laptop. 1 computer and the laptop are conected by a wireless internet router. Now, on the wired computer i can reach speeds of 10MB+ but on the wireless i am only getting 1.5MB or bellow. Is there a way i can make my router transmit faster speeds? I have a belkin high speed mode 125MB wwireless router, and a USB high speed mode adapter.