my 7600gt also performs about 100 points under openGL section of Xbench.
qe, ci, q2e enabled.
i tried ALL combinations of nv40 kexts, natits, titans, nvidiaefis and agpgarts, as well as different install dvds (JaS, Tubgirl, HotISO).
no improvement

i guess it has much to do with motherboard chipset, because one machine i installed osx on had 6600gt and scored about 125 (openGL).
that machine had nforce3 chipset (mine is via k8t800) - everything else was the same (cpu, mem type and quantity).