I recently removed a 128MB DDR-333MHz PC2700 memory stick and replaced it with a 512MB DDR-333MHZ PC 2700 module.  My computer is only recognizing an increase of 256MB.  I updated my BIOS, installed the larger module in the primary slot, and booted up with only the 512 module.  Did I purchase the wrong memory, or have I done something wrong?  Any help would be appreciated. 

Thanks,

Fancynance29