Apple computers are very expensive, but my wife and I have both turned exclusively to Mac in the last few years. Before I owned a 13 inch MBP, her HP, and a Fujitsu tablet. I've since thrown away those two PC's and a year ago I bought a 15 inch MBP for myself.
Reasons I decided to put out that kind of money:
-Durability. You pay for it. I travel a lot, I have a clumsy wife :), and I put my laptop in a backpack when I ride my motorcycle/bike a lot. The aluminum body of the MBP is extremely durable and does a fantastic job protecting the computer. No PC laptop I've ever owned has help up to drops onto tile like these MBPs wil.
-Software. I like OSX a lot. I work on Windows 7 during the week and it can be very frustrating when the simplest task becomes a security nightmare. When Windows 7 decides to do whatever the fuck it wants, or install updates whenever it wants, etc., I want to walk up to Bill Gates and smack him.
-Viruses. Say whatever you want, I don't care. I haven't had a single flicker of virus activity in 4 years on either computer. I download pretty much whatever I want too, so it's not like I'm that careful.
-Battery life. I know there are plenty of other good options if this is a huge concern of yours, but I replaced the battery in both my old HP and Fujitsu 3 and 5 times respectively because they simply wouldn't charge anymore. The wife's MBP still has amazing battery life and holds a full charge.
-The touchpad. If you've ever owned both a MBP and a competitors laptop at the same time, you know what I mean when you talk about how nice the touchpad is. It's seriously worth about $400 to me when I consider a purchase. It's huge, precise, smooth, and awesome. Anything less is a piece of shit.
-The screen. Enough said, just look at one. Even the old ones are impressive pieces of glass.
If you take care of a MBP, it can last a very long time. The price really isn't bad if you use it for it's full life, and you can very easily and cheaply upgrade RAM and hardrives for cheap at places like OWS online.