I've heard very good things about Gimp from friends, though I've never personally used it.  I got Photoshop recently, though, and I love it.  Whatever suits your needs, though.
How do you afford those programs?
 
Education pricing, I'm sure.  It's a wonderful thing.  I got Adobe's Web Premium Suite with Photoshop, Flash, Dreamweaver, Illustrator, Fireworks, Acrobat Pro, and a buch of programs I'm likely never going to use for $250 from my university's computer store.