I just did a fresh Windows XP Pro (SP2) reload and all is well. Except that the on board network devices never show they are connected. I have reloaded the drivers three times and same result. The XP Device Mangler shows no errors. The network cable that goes to that computer desk is live and works on other machines.
Shutdown then disconnect the RJ-45 cable from the MOBO, and restart. Open the Device Manager, click [+] Network Adapters - does Realtek 8111C/.... show-up? If not click the Scan for hardware or Options ? Scan for Hardware.
If it wasn't there before then you've got a bad cable.
Before going further, is the Realtek 8111C/... listed in the Device Manager?
...as I said it works on other computers at that desk.
Not always especially if it's off a HUB vs directly connected to the Router or Switch.
I'm looking at 'your configuration' it listed Asus P6T - is this correct? If yes then you need to delete the "Nforce networking device" it's loaded the wrong device. If not then please list the correct MOBO.