I haven't used GIMP but have heard good things about it, I use Photoshop Elements because have had it for years (is a much cheaper cut down version of Photoshop ($80 I think) but so far I haven't found anything that I am unable to do in it). If I wasn't so used to Elements (I am still on version 3 but I think they are up to 7 now) I would have a go at using GIMP. All depends exactly what you want to do - personally I would start with something free or cheap and see how much you use it and what you use it for. From what I have read for all but professional users (I just do image editing and artwork for fun using Elements and use it most days) GIMP can do pretty much most things Photoshop can.