I run Linux and Kismet (
http://www.kismetwireless.net) on an old IBM Thinkpad. 120 MHZ, 64 meg ram. Works great.
You can see it around 10 minutes into the "Wireless Point of Sale Security" video below.
http://www.lpbn.org/modules.php?op=m...ticle&artid=61
It's a nice shot with Kismet showing Petsmart and Best Buy ip ranges.