I was looking at EVGA's website, and noticed they sold the AC adapter normally included with the laptop on it's own. You can check it out here. If you look at the images, it is actually pretty tiny and much easier to fit into a backpack than a standard Alienware brick or Dell unit that most people use for their high power DC to ATX units.
The HD Plex 160w DC to ATX uses a 7.4 * 5 DC jack, I believe this unit has one as well, but I can't confirm. Seeing as it outputs a 19.5v wattage, would this be viable to use?

The HD Plex 160w DC to ATX uses a 7.4 * 5 DC jack, I believe this unit has one as well, but I can't confirm. Seeing as it outputs a 19.5v wattage, would this be viable to use?