Intuitiveness is a red herring
Nothing is intrinsequely intuitive, it's down to education. Something will FEEL intuitive if it obeys the same laws as something you already know. I always fire up my desktop calculator in reverse polish notation mode because I've learnt to thing effectively in stack-like mode. Your garden-variety user will feel that very counter-intuitive because they learnt basic math as <operand1> <operator> <operand2>. No method is more intuitive per se, it's just the way you're used to thinking at it that makes one or the other more intuitive.
When it comes to PCs (including Macs, as it should), there's another layer that comes into play: the line between "so intuitive that it does what you want without you having to learn COBOL" and "so intuitive that there is absolutely no way to tell what will be the output for a given input". I call the latter "luser-intuitive", and sadly that's how most "intuitive" UIs work nowadays. Then there is the "windows-intuitive" way, which sounds a bit like "so intuitive that you can crap your system completely without ever knowing how you got there". Sadly, that last level gains ground even on "serious" systems, as the Linux consumer-oriented commercial outfits see it as a way get into Wintards' pants.
So the really important thing is not "intuitiveness", it's giving the right tools to the right people.
If you are going to be your own sysadmin and you need to squeeze every drop of performance juice from your system (which means that you're on a tight budget, as otherwise you'd get a better system, obviously) then both Windows systems and anything from Apple are out of the question. Get an ugly thing from wherever and install a *NIX system on it (avoid the like of Ubuntu, PCBSD etc like the plague. Build your own tailored system with only the tools and services you need. When you choose your desktop environment don't even dare thinking about Gnome or KDE). For desktop-like use I would advise a Gentoo, or a Slackware. A Debian if you are prepared to fend off all the bells and whistles that will be thrown your way, but it can be difficult for a geek. The idea is that you will have to learn how your system works (how it really works, not how you can sometimes trick it into doing some stuff). so that you will be both able to use it efficiently AND to maintain it whithout doing too many stupid things.
If you have a sysadmin (Note for the retards: that means NOT you and NOT that guy next door who spends half his days on /. but is really supposed to type numbers in spreadsheets), then use whatever they tell you to and shut your trap. They DO know better. Actually, they're PAID to know better. And even if they did NOT know better, they WILL be the ones fixing your stupid mistakes so you REALLY want to be using a system that they know well. Even if it's a piece of shit.
If you never got around to learn how computers work, and you won't have anyone holding your hand through the configuration process, and you know that the only three pieces of software you could ever possibly need are available for Mac, and you've got more money than need for real computing power, then get a Mac. What could possibly go wrong? It's premium quality, lovingly assembled by asian workers from generic parts, and it's not like they ever got cracks or DOA problems or anything. At least the OS won't let you do anything blatantly stupid if you don't specifically ask it to. Actually some say that the OS won't let you do anything AT ALL, EVEN if you specifically ask it to, but these are lies. Or slight exagerations, at least.
If you're a cowboy at heart and would sooner die than read a manual, forget everything and install Windows. Preferably the alpha-test version (The one which is often cheekily labelled "Beta"). You can do it. Yes you're THAT good, don't listen to them. Knock'em dead tiger!