BIOS on 756 chipset...graphic aperture size??

well after going from my TNT 8meg to a GF2 Pro 64meg DDR, just looking in the BIOS and i have 2things my Latency clocks is at 64, is that ok, and the Graphic Aperture size is at 64MB, and the only other setting is 256MB which would be better for me and what is the difference

BUMP

If you are using a video card from Nvidia the normal aperture size is one half of the total amount of memory, but if you are using a 3dfx card you must dedicate the full amount of ram