It's crazy to use wireless when the PC's only 3 ft from the router. It sounds like you just need to get the right drivers installed to get the NIC on the motherboard to work. Otherwise, get an Intel NIC:
http://www.overclockers.co.uk/showproduct.php?prodid=NW-010-IN&groupid=46&catid=1597&subcat=
http://www.overclockers.co.uk/showproduct.php?prodid=NW-010-IN&groupid=46&catid=1597&subcat=