How about Gimp? It's a nice program, I think you can even install standard Adobe plugins on it...Yes, I know it has that separated windows thing, but I think it's worth a try...Can do almost everything Photoshop can do, it's a bit "different", so you'll probably spend a week or two getting familiar with where all the functions are, but...
Off topic: I've just realized I've reached 300 posts (this is 301)! Well, I should congratulate to myself
)) If it hadn't been for almost a year of being inactive, I would have probably reached 600 post by now