Once you become familiar with Aperture 3 you will relegate iPhoto to a place in history. It has replaced several pieces of software in my computer. The features in Aperture 3 made PS unnecessary for me except for perspective and distortion correction. I added PT lens to key software set to solve that problem with $25 solution. I tried two version soy LR and found no advantage to them over Aperture.
Richard Weisgrau www.drawnwithlight.com Author of The Real Business of Photography The Photographer's Guide to Negotiating Selling Your Photography Licensing Photography