Selection of Small Business Computer System

I have a photography/video business and need a new computer system for processing images and video. The problem is that it is difficult to compare the various products, especially Dell systems and Apple systems. Also, Dell seems to have different lines of computer systems, ranging from the XPS, Dimension, etc. The possible configurations differ, and it is difficult to know which one of the lines of Dell computers and configurations make the most sense for the image and video processing, in the range of $2800 to $3200 price tag. Dell, in its Dimension line, seems to offer dual quad processors and Apple calls it an 8 core system. Any suggestion on computer system lines and configurations for the purposes set forth above?