Things can only go so fast. I mean buying a Mac Pro expecting faster internet speeds is a bit ridiculous. You buy a Mac Pro when you need things like FCP, Aperture, etc.
iTunes can only que up a song so fast. You can only encode songs from a CD as fast as the drive will allow the data to come.
A general user will not be blown away by a Mac Pro when all they need is a $500 computer.
It doesn't matter what costs more or less. I don't even know why this is an argument anymore. What does anyone gain by thinking someone else is an idiot for buying product X when you think product Y is better? It is ridiculous.
Buy what you want. Done. If you want a Mac. Get a Mac. If you want a $500 windows box get it, a $2000 windows box get it. As long as you enjoy what you buy that is what matters. Be an informed consumer and make choices based on that information. This, I hate everything Apple so I am going to buy a Dell and a Zune is ridiculous. And this "Mac is better than everything else" crap is insane too.
You think Macs are better. That is fine! If someone asks explain why. Don't argue just list the points. If they say I disagree so be it! Ask if you can clarify something. If not let it go. I find all too often though that most people have no idea about the other side, they just spout off the crap they heard from sources on their side.
Sorry for the rant. I am just sick of these arguments. If the Mac is more expensive and doesn't offer you more value for that expense, don't buy it. Simple as that. And instead of finding figures to see who is cheaper, this is what you should be responding with.