I dig your style mate. Anyone who can make something good in photoshop is a-ok in my book (I can't work that stuff, haha)
Oh, I was working in GIMP for a while. But photoshop has better shading tools. I'm currently in a bit of a weird situation with Adobe and I have their products. So I sketch on paper, ink it, and then use photoshop for color+shading.
I tried a couple of free programs in the past that I didn't like.