I should add that if you are on OS X and know you won't be opening Photoshop files, Pixelmator has tons of great tutorials (http://www.pixelmator.com/tutorials

I should add that if you are on OS X and know you won't be opening Photoshop files, Pixelmator has tons of great tutorials (http://www.pixelmator.com/tutorials http://www.pixelmator.com/tutorials) for all skill-levels and is on sale for $15 right now. It can open PSDs just fine (including guides and editable text), but - at least right now - it has some trouble importing the look of certain layer effects that are also affected by opacity, the layer effects are merged/not editable and Smart Objects are rasterized/not scalable.