Ok, I just did that. It came up with a 46.55 second total computation time. Series computing time is 36.91 seconds, Division Time is 4.66 seconds, InvSqrt Time is 2.88 seconds and the Final Huge Multiplication time is 1.95 seconds.
Remember too, that these are the SE series Opteron's and are the JH-F2 Revision which feature a multitude of core enhancements (AMD Virtualization technology being a big one, not that it has any bearing here but just as an example.) So saying that it's "just" a 4600+ is not exactly accurate.
Joe