Hi
According to Microsoft "In general, if your PC can run Windows Vista, it can run Windows 7" -
http://www.microsoft.com/windows/windows-7/get/upgrade-advisor.aspx, so you shouldn't be worried too much

Anyway it's probably Gigabyte SATA2 RAID controller (servicing GSATA2_0, GSAT2_1 ports), which you don't use now.
So you can disable it in the BIOS: Integrated Peripherals --> Onboard GSATA-II Ctrl : Disabled.
Or if you want to use it in future then Win 7 drivers are available
here