Initially I got my MacBook Pro because I wanted to learn Final Cut Pro. For the first nine months, I was mostly concerned with that because I've been teaching myself everything I need to know for the Apple Certification exam.
But once I got comfortable with FCP, I started taking the time to really explore OSX and the more I use my MBP the more I love it. I eventually transferred all my old files onto it and I never use my desktop PC anymore. For the one and only Windows program I still use (Quicken), I have Fusion.
I don't have many PC horror stories, but I was getting sick of my Windows computer getting slower despite running virus checks, defragging, adding more memory, and all this other stuff to no avail. It was just a general malaise. My Mac just lets me zip through all the stuff I want to do and looks amazing, plus it's incredibly powerful.
I first started learning FCP at the local public access cable station about a year ago, I got my MBP in June of 08, got my own copy of FCS two months later, used the Level 1 certification book to teach myself the basics, got a job doing some editing in September, and I just passed the practice exam. Next week I'll take the real one and finding more editing work should be a lot easier.
So my MBP has quickly changed my life for the better.