I think an important part of comparing Apple computers with other manufacturers is to realize that Apple hardly ever gives any sort of discount. So MSRP of an Apple computer is what just about everyone will pay for it (+/- about 10% I would imagine). Whereas with Dell, HP, Lenovo, etc etc you can find deals all the time for far below MSRP.
For example. I have a Dell XPS 15 (latest model, L502x) that I bought about 8 months ago for $610. Core i5-2410m, GT540M 2GB, 1080p B+RGLED display (not IPS sadly, but it is still quite high quality), 6GB RAM, 500GB hard drive, has USB 3.0.
However if you went to dell's website and configured it right now (slightly newer CPU now and slightly bigger HD) it would cost $1049.99
To compete with price, I would have to get the Macbook 13" for $1200, but that's a major downgrade in screen resolution and graphics card (though of course an upgrade in portability and battery life). If I went with the 15" Macbook I would have to shell out a minimum of $1799 (over 3x the cost of my laptop).
For that extra $1200 I would get an i7 and a somewhat better video card, a good bit smaller and slightly lighter. It comes with 2GB less RAM, and a lower resolution screen (1080p vs 1680x1050)
EDIT: Actually the 1680x1050 screen is $100 more, the default is a 1440x900 one.
There is simply no way for me that those differences are worth $1200. I would pay maybe $300 extra for all that.
I had a similar sort of deal with a Dell XPS 8300 desktop with a Core i7-2600 for $400. The CPU itself still sells for about $300.
If you frequent deal forums like Slickdeals.net you'll see countless of awesome deals for PC desktop and laptops. Once in a blue moon does something better than 10% ever show up for an Apple desktop or laptop