I did most of my Photoshop work in Windows on the MacBook via Bootcamp since I had CS2. It ran fine, I was very impressed with the performance (had 2.0gb mem).
One thing to keep in mind is the screen real estate on the Macbook. the 13" screen was a little hard for me to work with in PS, but not impossible. I just had to zoom in a bit more on layouts. It depends on what you're working with. If full scale layouts, it might get tedious after awhile on the MB, but if just graphic work here and there, or touching up Photos, you should be fine.