I could maybe see this argument holding up a few years prior, but I think CS3 has had a remarkable influence on my workflow (compared to say, CS2). Having run the last 2 versions on the same Intel machine, there was immediate differences to note with the workspace and rendering times. I mean just compare the time it takes to load Photoshop and it justifies the upgrade.

I will be curious to see how lean the product stays when as the updates continue to roll in.