Improving model simulation speed
 

Hi all
I am looking to upgrade my PC to increase the speed I can process CFD models. I currently have an old 32 bit dual core Intel Xenon with 4 GB RAM. I am unsure as to what aspect of a new machine will give me the best improvement – i.e. processor speed or amount of RAM.
A possible machine I am looking at is a new quad core or 64 bit Dual Six Core model with 32-128 GB RAM. Can anyone advise on how much faster this new machine would perform when compared with the old machine, or advise on a better option? Would more RAM speed the simulation or would that just only limit the number of cells that can be simulated and not make any appreciable difference to the simulation time?
A typical model would be 4 meshes with a total of 2 million cells, although using more meshes would be possible to make better use of multi-core processors.
Any response would be much appreciated.
Mark