I came to Apple via the iPod. My first iPod (30GB Classic) expired (HD/battery failure) and, as it was still under warranty, Apple replaced it without fuss or seeking refuge or excuses not to do so. This happened a second time (some of the classics had a battery "issue") and, likewise, a replacement was issued without a problem as it was still under warranty.
Notwithstanding the various battery problems, I liked the form factor of the iPod, and the customer service Apple offered was excellent. Another factor which influenced me was a report I read on the BBC which argued that no Apple computer had ever been successfully attacked by a virus; initially, I assumed that this was mere propaganda or marketing, but I subsequently discovered that it was, in fact, true. At the time, on Windows, I was plagued by spam, and viruses, (despite having invested in the most robust anti-virus/spam etc software I could find) and very fed up with it.
So, I "switched" in April 2008 and bought a MBP. Since then, I have also bought a MBA, as I travel a lot and weight is an issue. I'll admit that I love the form factor of Apple, the good screens, the style, and build quality. OS is a very good system. In addition, I also like the customer support Apple give, and the fact that viruses are non-existant, and spam and its foul fellows have been hugely reduced (but not entirely eliminated).
Given the cost of Apple computers, and the fact that Apple honour their warranties, I always buy Applecare for computers; this means I have cover for three years, rather than one.
That does not mean that I hate Windows. Most of my work world still uses Windows, thus, I have to remain "au fait" with it, and, whenever I'm abroad, my work world seems to be "Windows" only. Likewise, I have Mac for Office on my Mac, as Word is what most of the - my - world uses. Moreover, I always had pretty good Windows laptops - I have had an Olivetti, a Toshiba Satellite Pro and a Sony Vaio and they were all very good laptops. However, I prefer the Apple Mac, but still find that I have to use Windows at almost any other desk or location than my own.
Cheers