Vista - Network Cable Unplugged

I have a home network that has a DSL modem connected to a Linksys BEFW11S4v.2
(with updated firmware) 4 port switch WiFi router. I have several XP machines
hardwired to teh switch and all have conectivity. I have a cable runnin form
the switch approximately 50 ft to an upstairs bedroom. I just purchased a
Dell with Vista for this room. The machine does not recognize teh cable. I
can carry my laptop running XP to the same room and connect the ethernet
cable and it works no problem.

I've downloaded new drivers for the internal NIC card on the Dell. Still the
Local Area Connection shows "network cable unplugged".

I've disabled IPV.6, QoS Stacker, Link-Layer topoloy discovery mapper i/o
driver and link-layer topology discovery responder and still I get "network
cable unplugged".

Frustrated eyond belief at this stage. Why does this have to be soooooooo
hard? Can you help me?