And the thing that people seem to forget in these comparisons is that if you actually want a laptop with the features of a Macbook Pro (or close equivalents), you will pay similar prices.
I have a $700 Dell Inspiron laptop next to me. It has a decent processor, 4GB of RAM, 250GB hard drive. A close performance analog to my Macbook Pro. But are they the same? Hardly. No DVI out (or Display Port); a 1366x768 resolution, which is just awful on a 15" screen; a flimsy plastic case I'm afraid of breaking; no Firewire; no Gigabit ethernet (10/100 only); no Wireless-N (G-only, which slows my whole network down).
And, of course, a 2.5-hour battery, which I can get a second of for a mere $180.
It's certainly possible to buy a laptop with a "better" processor in it than the ones Apple is offering. But it's important (and most people don't do this) to look at the big picture. What ELSE does the laptop offer you? I could put an i7 in my Inspiron; it still wouldn't make it a better COMPUTER than my Core 2 Duo MBP.