Try this link to CPU charts at tomshardware.com, the application tested is 3Max and is the overall speed of the rendering (smaller the better) for various CPU's (including I5 & I7).

Unfortunetly they stopped testing 3d apps lately so this one is a bit old but I figure render time is probably a factor in your purchase.

Note: I use an i7 920 which comes up as 8 threads on taskmanager and all are slamming on V9C no problems, just wish I had more ram;)

 

http://www.tomshardware.com/charts/2009-desktop-cpu-charts-update-1/3DS-Max-2009,1380.html