The Apple Mac mini has been around in one form or another for almost three years, and while the internal components have changed, the general concept and overall design has stayed the same. Pricing starts at $599, but the one we looked at is the upgraded 2-GHz $799 model. It's one of the forerunners of the green PC, having gone through several generations of substituting energy-efficient notebook-class components for desktop parts since the G4-powered Mac minis of early 2005. The Mac mini has been the lower-priced, entry-level Mac, but now that it's equipped with the Core 2 Duo processors, it is as powerful as a larger desktop while retaining its power (and space) savings. The Apple Mac mini appeals to both space-constrained and green-thinking PC users.