SG-72 Socket 478

I have an Intel Cel 2.66ghz that l previously had in an Asus P4S533 running
with SDRAM. Everything worked fine but l thought l'd upgrade to DDR. I
went out and bought an Abit SG-72 with some DDR PC2700 thinking that it
would be fine. On the old Asus the Auto setting for the CPU had you select
either 2000Mhz or 2667 Mhz when running with older PC133 RAM. Of course l
ran it at 2667 and it was fine. Now with the Abit it seems to lock the FSB
and mulitpliers at 20x100mhz, even when l change the FSB to 133mhz. The
PC2700 should be 512Mb but only comes up as 328Mb. I've set the CPU FSB as
133mhz and the DDR as 166mhz but l still only get 2000mhz and the RAM
refuses to post. I placed an older PC2100 stick in there and it posts fine
but l still can't get 2667 mhz out of it. It's running the latest BIOS on
Win XP Pro and there's nothing else out of the ordinary that l can see. Any
suggestions?

Doug