Here's the skivvy. The AMD driver is for the 6 'light blue" SATA ports which are supported by the AMD SB850 southbridge. The Gigabyte SATA driver is for the two "white" SATA ports next to the AMD ones supported by the Gigabyte SATA 2 controller. Here's a pic of the board:
So, depending upon which ports you have your hard drives connected, that's the driver you need. Personally, I prefer to use the AMD ones for my internal drives and the Gigabyte ones for external e-SATA connections.
The manual TemplarLord linked shows a diagram of them on page 8, along with RAID setup instructions beginning on page 77 for the AMD SB850 controller, and page 83 for the Gigabyte controller.
Also of note, Windows 7 (and Vista) has have built-in RAID drivers, so a setup disk is no longer necessary for Windows installation. XP still requires such a setup disk, which is why the "Press F6..." message is still used. While I doubt the drivers need updating, you can update them if you wish. But I'd go to AMD's site ( http://sites.amd.com/us/game/downloads/Pages/downloads.aspx
) and get the southbridge/RAID drivers there. Find them by choosing your Windows version under the Motherboard/Integrated Video list, then under the "Optional Downloads" tab.