My company uses a standard laptop with an Orinoco card in a dual-boot fashion. We bought a cheap antenna for the wireless card, although you can make one using a Pringles can (as described at https://www.turnpoint.net/wireless/cantennahowto.html). We have both Windows 2000 and Linux installed on the laptop. On Windows 2000, we run Netstumbler to discover wireless LANs. On Linux, we use Airsnort to sniff and break WEP keys. A $150 GPS receiver with serial-port connection rounds out the set up for recording geographic locations.
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