I use Photoshop, but only because I got it at a really good price a couple of years ago. Before that I used Photoshop Elements and found it very user friendly. When I was using it and updating it it cost about 100 bucks....not sure if it's gone up or not. I think they are now on PSE 10 or 11.
My nephew told me about Gimp and he said it is every bit as good as Photoshop....haven't tried it myself so can't attest to that, but I thin it might be worth a try.