Personally would recommend a all-in-one unit. Something like Netgear DG834G if you want wireless (£90 including free adapter)click here or DG834 for wired (four ports) click here
click here is good for all brands of kit.
Ditch the usb modem. There are no problems with using routers and BT. The only reason it may be worth moving is price (BT is expensive) click here