As far as I'm aware, the true story is that Apple paid Xerox a hefty amount of Apple stock in return for Steve Jobs and others being allowed to take a tour of PARC. The question is, was it envisaged in this deal that Jobs and co. would be allowed to lift whatever concepts they came across on that tour? The amount involved seems rather large if Apple were simply to stop by and see what Xerox were up to, and then go home without taking any notes.
I generally don't agree that the ends justify the means, but in this case I think we should be glad Jobs stole/bought the GUI concept from Xerox, as they weren't about to do anything useful with it.
There are numerous other stories from Apple's Lore, including the one where Jobs stiffed Steve Wozniak for money he collected from Atari for work the Woz had done. Then there's the one with Jobs standing with (then Pepsi marketing supremo and later Apple CEO) John Sculley on a New York rooftop and asking him: "Do you want to spend the rest of your life selling sugared water, or do you want a chance to change the world?"
There are several books filled with Apple lore, they're generally pretty good reads.