Well ATI vs nVidia is a personal preference really
And about the monitors, you can plug a console into them, via HDMI, as I'm doing that now myself (1 screen is PC, and the other is my Xbox), and because they have quite a few connectors, you can plug more than 1 thing in (2 HDMI, 1 DVI, and 1 VGA) and easily switch between the two. They also come witha DVI and a VGA cable, and they have built in speakers too, so the Xbox sound comes out the monitor itself, instead of having to hook up a seperate set of speakers. And if you have a sound system, you can use the on-board sound of the motherboard, or get a dedicated sound card, but the quality of on-board sound these days is amazing