I think the 9400m and 256mb of VRAM and 8gb of memory would be more beneficial. I think the previous Mini would only go up to 6gb and have Intell GMA graphics.
The 2007 Mini, the model preceding the 2009 model, can only go to 3.3GB of ram. Still, a 2006/2007 Mini would be an excellent machine for the uses outlined by oldhifi.