I have Adobe Photoshop 7 that I got at a student discount when I was taking some night classes...when it opens up it states "for educational use only". I don't use it too much anymore so my skills are rusty and limited. I did my own sig FWIW

 

I've got CS3, and I've used Gimp and now I have Paint.net on my laptop, which is also free and fairly powerful yet I think it is easier to use than Gimp. I'm not all that good at any of it tho.