I found the mecca of geekbench scores
Performances (June 2007)
iMac G5 1.8 GHz @ 1044
Power Mac G5 Dual-Dual 2.5 GHz @ 3284
iMac C2E 2.8 GHz @ 3791
Mac Pro Dual Dual-Xeon 2.0 GHz @ 3894
Mac Pro Dual Quad-Xeon 3.0 GHz @ 8618
I can't wait too feel the power.
iMac 2.8 from a geekbench test seems pretty good.