For the SS56G to support 1GB DDR modules, users are required to update the BIOS to FS56S01H or later. You can download the BIOS from the Shuttle website at :
http://www.shuttle.com/hq/support/download/dwn2.asp?model=SS56G
Refer to the "How to use Winflash utility?" FAQ for instructions on how to update the BIOS version.