Yes, that's right. Rendering seems to be pretty much CPU-dependent. After 512MB of memory - more memory doesn't seem to add anything to rendering. But more memory has a significant effect on modeling (loading objects, moving them around, etc.) I have a dual CPU system - these really speed up my rendering, so you might want to consider a dual CPU system if you think you'll be doing much 3D work. Almost every 3D program I use takes good advantage of 2 CPU's. These help in modelling too. Nvidia seems best, to me at least.