Apple Spec Int and FP numbers. here. AMD Opteron Spec Int and FP numbers. 2CPUs Int, 2CPUs FP (I won't bother comparing 4 CPUs against 2 Apple CPUs, even though Apple seem quite happy to compare 2 G5s to 1 P4). Also if you look at the figures for the 2x Xeon 2.8ghz: Int 19.6 FP 14.7 on AMDs site vs Apples Site 2x Xeon 3.06ghz: Int 16.7 FP 11.1 you wonder why Apple are "flavouring" the benchmark results.

AMD Dual Opteron 244 Int : 26.8 FP : 26.7 vs (note Opteron is running at 1.8Ghz)
Apple Dual 2Ghz G5 Int : 17.2 FP : 15.7 vs
Intel Dual Xeon 2.8ghz Int : 19.6 FP : 14.7 (from AMDs site)
Intel Dual Xeon 3.06ghz Int : 16.7 FP : 11.1 (from Apples site)

If you can be bothered, you can confirm the AMD, and presumably Intel, results at spec.org/cpu2000. and while i'm at it: some people wonder when Linux will have more market share than Apple....?

Other sites that question the Spec scores : apple guy [slashdot waffle], AMD Zone [the inq.]. and some more comment about the performance of the G5 from a mac person. if you're not completely bored by it all yet, then there's a fairly good post here about it. and some semi-amusing pics here.