How to Tell If NIC supports Gigabit Ethernet
Solution 1:
Go to Device Manager, and go to the properties of your network card.
In the Advanced tab, find the Speed & Duplex setting. The value of this should be "Auto Negotation", however, in the dropdown there is a list of speeds the card can support. If 1Gbps is in the list, the card supports gigabit.
Leave the card set to auto-negotiate.