Physically check your ethernet card. You should have the manufacturer's name on it as well as the protocole number (e.g. mine is a realtek RTL1839).
Next, click on install new hardware, select from list, and select your manufacturer's and RTL protocol. This should do the trick. Once that is done, don't forget to delete the ones that don't work in your device manager.
My gaming machine:
P4 2.8 GHz
2 X 512 MHz PC3200 in dual DDR mode
Intel D865PERL MOBO
integrated 6.1 MAX audio
Logitech duo MX mouse and KB
ATI RADEON 9800 PRO