My God does this question get asked a lot! You just one of the pat answers. However, the GIMP is an X11-served, opensource alternative to Photoshop. As such, it is massive overkill for someone who is used to MS Paint. There is an "Aqua-native" massively cutdown version of the GIMP called Seashore. IMHO, Seashore looks like dog vomit. Professional level Macs ship with GraphicConverter and Apple pays the shareware fee for you. This wonderful app can handle just about every graphic format since 1937. It accepts Photoshop plug-ins. It can be used as alternative to iPhoto. It is just as easy to use, if not easier to use, as Paint. Suffice it to say, it is much more powerful. If it did not ship with your Mac, it is a must-download. It is fully-functional nagware if you don't pay the shareware fee.