Hi Simon,
At the risk of being called a "fanboy," I have to add my two cents to the Apple camp. I know there are exceptions, but generally, when you buy an Apple product, you just take it out of the box and it works. I have spent literally days trying to configure and set up a new PC.
I have an early-2013 13" MacBook Pro with Retina display. It is pretty much maxed out with the 3.0 i7 chip and 512 gb SSD. I only wish I had gotten the 768 gb SSD instead. Otherwise, it's perfect. I have Windows Ultimate 7 installed in Bootcamp and it works great too. As an aside, I use Winclone 4.2.2 to regularly backup the Bootcamp partition to my Time Capsule.
I realize there are pros and cons to everything, but if you can stand to spend the bucks, I recommend going with the MacBook Pro. I like the 13" because I take it with me on the road, but a 15" doesn't weigh much more and has even more computing power. I think you'd be happy with either, especially since Mavericks has been released, It includes several great productivity programs you'd pay a lot extra for with a PC.
While I'm typing, let me thank you again for making this website available. It's a priceless asset to those who are or have been trapped within the Watchtower's tentacles. Keep up the good work!
Regards,
Radar