The landscape has taken some changes for the worse since late 2001. Linux compatibility and open-source drivers have not been released or supported by some of the newer chipset vendors on the market (Atheros, Texas Instruments), so these devices are unusable by any operating system other than certain versions of Microsoft Windows. Avoid chipsets from these manufacturers, lobby the vendors for support of Linux and other operating systems. The older generation of chipsets from vendors such as Cisco/Aironet, Lucent/Avaya, and Intersil, are far better supported and work well. However they do not support transfer rates of faster than 11 MB/S.
802.11 equipment is made for use inside a small office or home, and requires some beefing up to get decent range. The insignificant antennas that come with the consumer equipment should be replaced by something more substantial for better range and speed. There are instructions on Guerrilla.Net for some good omnidirectonal antennas. Aerialix offers fully assembled antennas and kits. Homebuilt antennas constructed from Pringles potatoe chip cans have the appeal of light, cheap, and easily obtainable parts, but suffer in their inefficient design and physical robustness to the point the relegates them to something only suitable as a curiosity and bait for amusement-furnishing reporters.
My hand hurts, I'll type more later..