To increase ur physical memory u dont have to decrease the VGA aperture size
I have AMI-Bios and this is the way I increase/decrease my shared memory.
1. Go to Bios by pressing <Del>
2. Choose <PNP/PCI CONFIGURATION> frm Main menu of BIOS.
3. Configure <OnChip VGA frame buffer> between (8/16/32)MB......Dnt choose 'none' if u dont have Graphics card.
Save and Exit
You can check ur available Physical Memory in Taskmanager
~Cheers