I don't think the GIMP is magical, it's just pretty much what Photoshop is, only free (and Open Source). Wait, that's pretty magical... =)

If you are really going to try it, make sure you get a 2.2.x "developer" version so you get the latest features. I think the Windows version is 2.2.x. Don't expect the same control-keys Photoshop uses. All the shortcuts and a lot of the controls are different. It's frustrating at first, but so was Photoshop when I first learned that.

Love, Roz

P.S. All of my Gridcosm panels this year have been done in the GIMP (I think).