Out of interest - I am on telstra cable triple package at home = tv+phone+40gb with a Linksys WRT54g wireless router in roof connected via ethernet cable to xbox / master pc.
A Cisco SRP521 would be your best option. Would replace the Linksys WRT54g, and it's WAN port would be connected to you cable modem. You can then wire in the FXS port (phone port) into your existing home phone wiring to run your existing phones. Make sure your phone wiring is cut off from the outside world - or get someone in who knows what they are doing to set this up.
Alternatively as Steve says, get a triple DECT cordless phone pack.
Or you could go with something like a Snom M9, or others have tried various Siemens IP cordless DECT phones.