I am on Virgin broadband and have a 20mb connection which gives me speeds of about 16 -18mb
If you connect to the router by wireless your connection speed will drop, the max is 54mbs but of course this is never achieved in practice.
I assume at the moment you have the Virgin cable to a modem a cable from modem to WAN port on your router and a cable from the router to your PC and your sons laptop connected wirelessly.
Does your PC have a wireless card? If so just use the wireless setup wizard in control panel and use the same settings as your son has on his laptop for SSID and security password/key.