Just.. on the side with this.. sometimes, there will be a feature or operation that is more easily done in another app... also, at times, there is something that YOU can do more easily in a different program, simply because THAT particular feature/operation is more familiar to you in the other one. I find The Gimp to be useful when I want to manipulate alpha channel... true, I could use CS5 but The Gimp is more familiar when I am.

  have you ever used Illustrator? yes, I know, it's Vector Vs Raster, but you can see, even with the difference between the two that there are SOME things that you really should be able to do in, say, Illustrator, but have to do in PS.. and vice versa.

"..... and that was when things got interestiing."