I think it’s one of those situations where if you have to ask, you won’t know the difference. I use Photoshop Elements 7 for light-duty web work. And I play in Photoshop contests like this (the first image is the original, the rest are entries). Only two limitations bother me – the text-on-a-curve tools are weak, and I can’t punch in numbers to scale an image, I have to drag it and watch the numbers in the ‘Info’ window. For $500 I can work around this. If I needed more, and did not have the budget for CS4, I would switch to the free, open-source The Gimp