For rendering with Maya, most often than not more/better processing power is better for most things.
And not just CPU, but also a good GPU in your graphics card pipeline.
A great quad-core machine is nothing without a quality video card that is recommended by Autodesk
I honestly cannot speak of ram usage as a major NEED for most things in Maya, as much as the following:
Ram and fast drives/arrays are where it's at for fcheck playback, and all your post work.
Did any of that help at all?
Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS