Try the Vista 64 bit version instead.
Set a restore point and if all doesn't go accordingly you can uninstall the driver and go back to the restore point to reset any registry changes.http://www.gigabyte.com.tw/Support/Motherboard/Driver_Model.aspx?ProductID=2456&ost=others#anchor_os
You need the LAN driver listed at the top.
Hope all goes well.
Microsoft claim that the hardware is 100% compatible with Win 7 X64.
If you have the CD that came with the MB you should be able to load it and run the automated installer, this is what I done with my Gigabyte GA-P35-DS3P when I had Windows 7 X64 RC1 installed.