I can't really say much for Aftereffects or Pro Tools, but Photoshop (I'm assuming CS3) works only a bit slower than a Macbook Pro. Most things in Photoshop do not really utitilize the graphics card, so it mostly comes down to processor.
I'm not sure how it compares to the P4, but I believe (correct me if I'm wrong) that a dual-core processor, albiet a slower one, will perform better in most Photoshops things if not all, as they work more effeciently with the work being done.
Unless your using programs with really demanding graphics work, such as Motion, then the Macbook should suit your needs. I had a Macbook (gave to my sister), and at times some things basic system tasks seemed snappier (ram upgraded to 2GB) then my current 2.2 MBP.