I have a two month old laptop and just tried to use the NIC (been using wireless up until now).
Initially I could get the NIC to work occasionally (it would take ages to acquire an address), but when connected it would only ever do so at 10 mbs. Even the router showed orange light to confirm 10 mbs.
I swapped cables and ports on the router with other computers on the home network to no avail. All other computers connect fine at 100mbs.
So I unistalled the drivers (XP was telling me drivers were up to date). On re-boot the NIC was detected and drivers loaded - which were a newer version.
Now the NIC won't connect at all - just says cable un plugged.
Ended up being the router. Even though the wireless side of the router was fine, the LAN side started to slowly fail due to cooked capacitors caused by the wireless overheating the whole device.
This slow death is what threw me as some computers were still connceting at 100mbps, others at 10mbps and some no connection (like the laptop). After a couple of days no computers could get a LAN connection but wireless was fine.
It is an Australian router and I discovered on an OZ forum that it is a common problem with this make. You can actually replace the capacitors but the device is 3 years old so I think I will just buy a new router.