Dual Opteron 275: 1min. 10 sec.
Dual Xeon 3.4GHz: 2 min. 7 sec.
Great that 3ds max is properly multi-threaded (readily apparent from the utilization charts for each CPU core). The Opteron pulls ahead because it is Dual Core, and it does have a very efficient bus between the cores and even between the CPUs. Well ahead of Intel, and this has not been lost on the workstation makers.
I always stayed away from AMD CPUs due to the continuous problems with the awful VIA chipsets.
Now it seems that AMD has gotten serious and they have taken control of the peripheral chips.
Remarkably you can buy a single core Opteron today and then just drop in a dual core when the price has come down to whatever level you like. This even actually works according to several reviewers.
Apple would be able to play in the same league if they used IBM's Power5 CPU, which has a very advanced 64-bit multicore architecture. There is of course speculation that Apple will do just that sometime this year.
It's a bit confusing, but Apple G5 computers use a PowerPC CPU based on IBM Power4. Let's hope the G6 uses Power5...