The only reason not to get a Mac is that you have to go into the awful Mac store where a carefully selected team of good looking, tidy, and carefully multi-racially represented twenty year olds (without a deep knowledge of computers), with trendy, youth accoutrements such as facial piercings and dreadlocks (short, neat dreadlocks), will ignore you for ages if you are over thirty-five, even though you walked in with a thousand quid burning a hole in your pocket and the intention to buy a MacBook Pro.
They'll fawn all over the kids running in to the store to buy a new iPod touch and ignore the best customer in the store!
Anyhow, rant over, I love Apple computers, for these reasons:
The way the OS works, you find yourself archiving things and customising the computer to suit your own personality, more so than on a Windows system.
The computers come with every single thing you would want, software-wise, except the Microsoft office suite, which most people feel they need, although there are alternatives that create Word files and Excel files. The security is tight, and regularly updated, so there is no need to shell out on virus software. There are lots of nice, user friendly and intuitive applications already installed to help you archive music, movies, photos, create movies, edit photos and so forth.
You never have to install a driver for any peripheral.
The customer service is terrific, under warranty (and this can be increased to three years with Apple Care) you can call them any time (I use the US number after hours) for help with anything that goes wrong with the hardware or software. And it is worldwide. Your mac goes bung in Tokyo or Toronto and there's a store there to fix it for you.
One crappy thing is... the hardware has become less reliable in recent years, and after many years of producing bullet-proof laptops, I have heard stories lately of problems with overheating (I think this was solved with the latest MacBooks), batteries dying, amongst other things. I hope this is not the start of a slippery slope in product quality. Anyhow, the guarantee will cover any breakdowns.
Regardless of these reservations, I would always recommend a mac over Windows. They are used extensively in education, the creative industries and more recently at home. Apple are always increasing market share and it is no longer considered a niche product or an "outsider's choice". And yes, it can run almost any application, and for those that are Windows only, Apple can also run Windows.