I once compared an 18-105 to a 20 f2.8 prime. Aperture by aperture... the zoom won the sharpness test all over the frame. Plus, f3.5 with VR against f2.8... in my book the zoom won again. Plus, being paid for, as opposed to buying, guess what: I kept the zoom and went happy about it.
http://egozarolho.blogspot.com 1. Good content, good aesthetics and good tecnique. On that order. 2. Light is more important than glass and pixels. 3. In the digital photography process, software is as important as gear.