You could try right clicking the Network Controller in Device Manager and select Update Driver then point it to where you've saved the extracted files mentioned above. The other thing to try is to right click on the Netrtxpo.inf file and select install.
I am Spartacus; as I've said, pointing the install wizard at the folder - it just ignores it, evidently something not right! Devil Fish; The install wizard won't let me explore further down than the folder "WinXP". and the .inf file is in there!! weird or what!
Is this a device where the software needs to be installed first, if so perhaps you need to disconnect or if it is a PCI card then it might have to be taken out (PC switched off); reboot and install the software etc and then re connect how ever.