Using drivers from MS can be problematic. Try the drivers offered by the manufacturer.
While you are in Device Manager check that the NIC is installed properly.
Try another NIC.
I just reinstalled a spy ware ridden Dell 4300 running Windows XP, with a Cnet NIC card. Upon reinstalling XP, the computer can no longer see the linksys 8-port router or connect to the internet, even when directly plugged into the cable modem.
I have tried installing the latest drivers listed on the Microsoft Windows Update Driver Database, reinstalling the NIC in the hardware database, configuring everything known to man, and nothing has worked. The lights on the NIC and the router both light up when the cable is in, and when unplugged from the router, XP gives me the nice little notification that a network cable has been unplugged. When plugged directly into the cable modem, I still cannot connect to the internet. I also cannot see anyone on the network. When I ping the Linksys router, it does not even detect it and times out each time. I tried switching ports, and this makes no difference. I also have not received any packets, save 1 (immediately after reconnecting to a different port).
I don't suspect that it is the hardware, as it worked before reinstalling XP. I suspect that it is some sort of software settings. I have not released the DHCP over the entire network, as the computer doesn't even see the network. All other 4 computers on the network see everything else just fine.
I am at a loss for what to try. Any suggestions? I'd appreciate any help anyone can offer.

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