Don't get an internal card, since you will need a card per laptop. Go with the external that plugs into USB.
You can get a mobile router if you need multiple laptops connected on the road - [ame=http://www.amazon.com/Cradlepoint-CTR350-Cellular-Travel-Router/dp/B000UO18FC/ref=sr_1_2?ie=UTF8&s=electronics&qid=1250346604&sr=8-2]Amazon.com: Cradlepoint CTR-350 Mobile Router: Electronics[/ame]