I know there is a lot of hardware enthusiast out there using Blender who spend a lot of time tinkering with their computers. So why don't we start collecting some data on Cycles performance using a single test scene.
Image for illustration purposes, some effects are photoshopped.
Download benchmark scene from http://dl.dropbox.com/u/1742071/1m/BMW1M-MikePan.blend
Render and post result here
The result can be viewed from this spreadsheet