I'm wondering the same thing.
Have a Gigabyte GA-K8NXP-SLI motherboard, with two embedded gigabit ports,
NVidia and Marvel. Have the latest drivers installed from the chipset makers
and 1000MB is not available for a speed, only 100MB. Autonegotiate to a 3Com
OfficeConnect switch only yields a 100MB connection.
Wierd, would like to hear other experiences.
RK