For me, I always take a laptop hands down over a desktop. I have yet to own a mac (though I am very pro Mac, I just find my pocket book favoring PCs). From my PC laptop experience, I can say they break down a lot more (I have owned three different brands too, so it isn't just the brand) and parts are a lot harder to get to fix them and a lot more expensive too. However, I am not sure how easy Mac desktops are to fix, so in the Mac world it may not be that different. Desktop PC are incredibly easy to pull old hardware out and throw in new hardware, while laptops are a pain in the rear end to pull apart.

I like to think Apple takes a lot more pride in their products than other companies, I know this used to be fairly true, not sure about now though. But every laptop I have ever owned broke down within the first year, so I always made it a habbit to get the extended warranty. But like I said, Macs may be a lot more sturdy.

Also from my experience, laptops are never as powerful as desktops (pretty sure this would be true for Macs as well), since you need a powerhorse for editing, you might want to go with the desktop. Hope that helps some. A real Mac user like Jay will be able to give better input though.