I do a lot of 3D artwork, so I use a variety of programs, but in painting, Photoshop 6 and Painter are my weapons of choice. I know PS6 is old, but I'm comfortable with it and it does what I want it to do.
I basically use C4D, Bryce and PS CS2 all together. Mostly to work on sigs and abstract. A lot has changed in CS2 and takes a bit of getting used to but I like it.