I don't have this board but in case not one else answers...If I were you I would go with Windows 7.
I see on Gigabyte's web site that they at least have an audio driver for your motherboard that works with Windows 7. That is encouraging. It is very possible that Windows 7 itself has all the other drivers you need included with it.
You can download and install the Windows upgrade adviser from Microsoft to see what it says.
Windows 7 Upgrade Advisorhttp://www.microsoft.com/en-us/download/details.aspx?id=20BTW, Back in 2006 when Vista was coming out I had a motherboard with am Nvidia nForce2 chipset. I thought about upgrading to Windows Vista so I tried the last test version which was Vista RC2. It was such a memory hog on my old computer I stuck with Windows XP. I tried again with Windows 7 and was surprised that it worked better than Windows Vista ever had. I think I remember that driver support included with Windows 7 was better than Windows Vista also. Not bad for a chipset that came out in 2002.