The actual computer that all the displays are hooked up to is a Dell studio XPS 9100, with 2TB memory and 12GB ram. Right now it only has a single AMD Radeon HD 6700 graphics card (will probably upgrade with a second at some point). It also has some fancy audio card, but I don't use it for audio stuff, so that's not important.
I'm fully aware that Macs are considered the design industry standard for computers, but based off the cost versus performance, I just can't bring myself to buy one. A Mac with the same technical specifications as my computer would have been approximately three times the price. And personally, I like the levels of customization that non-mac computers allow - both physical components, and the interface. That, and the main program I use for inking, Paint Tool Sai, is a windows only program.