nforce4 ultra vs nforce4 sli

Hi all,

Looking to build a new amd 64bit system. I am a bit confused regarding
nforce4 ultra and nforce4 sli chipsets.

Would i be right in assuming the nforce4 sli has everything the nforce4
ultra has and additional sli support, or do they both differ in other ways?.

If i got a mobo with nforce4 sli chipset but only used one pci card as i
intend to would that lower performance for any reason.

Finally looking at the Abit AN8 Fatal1ty SLI mobo. Is there a better mobo
for gaming performance, not into OCing just want best performance from games
(perhaps not the right NG but im sure theres plenty of gamers here!).

Thanks for any info.