The Mac vs PC is an endless debate.
That being said, the following is based on personal experience.
Last year I moved to New Zealand for graduate studies, and purchased a maxed out Lenovo T510. At the time there weren't any quad core, but that model was offered with a 1920x1080 screen. In addition, Lenovo has a 45% discount special (circa September 2010). At the time the equivalent Apple computer was more than double the price I paid(with discount factored in).
I also purchased an ultra bay HDD rack to replace the dvd-rom and install a secondary HDD. I've used this setup for the past 18 months, used it in New Zealand as well as in Europe where I currently am. The laptop is still solid. I've dropped it a few times, I've even spilled tea twice on the keyboard..... Its solid, its built like a tank and as far as using for photo editing it's been performing beautifully since day one. It's also great to easily swap drives from the HDD ultra bay.
There are better laptops out there spec wise and I don't know it lenovo runs deals like it did when I purchased mine, but for the money, I still think at the time it was the wises investment, especially that beautiful 1920x1080 95% gamut screen, simply stunning.
If I was to replace my laptop I would certainly get Lenovo's latest T5XX model.