USB or dock is only if you want to expand on your current laptop. If you're buying a new laptop you simply buy one with dual-out, (like DVI + HDMI), such as the Dell XPS for example. Then you are ready to plug in two external screens with no extra hardware. This is for a "travel setup". However, if you are looking for a setup to be at ONE additional location where you just leave the screens, then a dock is nice, as it's quick and easy just to smack the laptop into the dock, no fumbling with cables and stuff.