MacBook : Core 2 Duo 2.0Ghz, 2.5Gb 667 Ram, 80Gb Hard Drive, Leopard.
2686
Very close to my results, you have 500mb more RAM and are running Leopard.
The results depend on what else is running at the same time. I ran it again after closing Safari yet the result went down which was odd. Bottom line is variations are expected.