Ok so I've added a 2nd Laptop into the Mix.  For a total of 6 systems and the Render time dropped down to 1:38  a savings of 51 Seconds.

This is very interesting to me and without knowing the actuall internal logic, It almost looks like that Even number of PC's render fast than odd numbered.

So for a re-cap the results are as follows.

1 x CPU = 10:25 Pentium 4 HT 3Ghz
2 x CPU = 05:17 Pentium 4 HT 3Ghz
3 x CPU = 03:34 Pentium 4 HT 3Ghz
4 x CPU = 02:38 Pentium D HT 3Ghz.
5 x CPU = 02:49 Core 2 Duo T7500 @ 2.20 Ghz
6 x CPU = 01:38 Pentium Dual CPU T2370 @ 1.73 Ghz.

I'm comparing my results to the test file I got from  here: http://www.horo.ch/raytracing/tests/rendertest.html

and you can see that a Single Core i5 on a Mac can render the same scene in 41 Seconds, while a 2 x Xeon QuadCore for a total of 8 cores pumps it out in 46 Seconds.

So what do you guys think?  Now these tests are being done on a Single Frame.

I should do an animation and see what kind of results I get.. I wonder Bryce Lightning would behave different.