Why has Windows beat out Mac over the years? One word: Games
Now before you discount what I'm saying just hear me out. Unix was arguably the first real operating system. Why was it created? To play Space War. Not so it could do enterprisy things like databasing and spreadsheets, but to play a game. Over the years people drop huge wads of cash on new hardware not so they can do better word processing, but so they can play the latest game.
Apple didn't embrace the gamers the way Microsoft did. People bought computers at home for playing with, and as a trickle-down effect wanted the same machine at work as the did at home. Oh sure all the big money is in the enterprise with big iron and lots of expensive licensing, but it's been games that drew people into computers in the first place and it's games that keep them there.
What do I think Apple should do? Buy or partner with Nintendo and start hooking the Mac to a game platform. Until I can go to my local Staples and buy the latest cool title for my Mac, it ain't gonna unseat Windows, no matter how much better it is.
By the way, I'm a Mac user. I'm also not a gamer :)