You do not want Gigabyte-branded drivers. Since you have an older card, you will want to stay with a legacy video card driver with SDK 2.5 included.
First uninstall all ATI/Gigabyte software, reboot.
Then you must manually remove these files that are not removed by the uninstaller:
C:\Windows\System32\amdocl64.dll
C:\Windows\System32\amdoclcl64.dll
C:\Windows\System32\OpenCL.dll
C:\Windows\SysWOW64\amdocl.dll
C:\Windows\SysWOW64\amdoclcl.dll
C:\Windows\SysWOW64\OpenCL.dll
Then get and install this driver package, which includes AMD APP 2.5:
http://www2.ati.com/drivers/11-11_vista64_win7_64_dd_ccc_ocl.exeAdditionally, you will want to grab overclocking software such as Sapphire TRIXX or MSI afterburner to
underclock your GPU
RAM to ~300MHz for the most efficient mining.