I just registered to this forum. I have a number of wifi adapters I have tested and I will post my experiences here. List of adapters tested: Alfa 1000mW AWUS036H (RTL8187) 7 dBi Panel Antenna and 5 dbBi Omni Directional PowerLink PL-18N 600 mW (RT3072) 9dBi Dual Antenna Generic 400mW 5dBi Antenna (RTL8187B) Gsky 500mW 27dBm (RTL8187B) 5dBi Antenna TP-LINK - TL-WN722N 100mW (AR9271) 4dBi Antenna Etekcity (Sinmax) 1000mw (RT3072) Dual 6 dBi Antenna Antennae all detachable. Separate Antennae tested: EnGenius EAG-2408 Outdoor HighGain 8dBi Omni-Directional Antenna BilcoWifi 20dbi Cantenna I use the Linux OS almost exclusively. I have noticed that the 8187 chipset seems to work better with Windows than with Linux, by that I mean they have a more stable connection to an AP with better data through put. All the adapters work with Linux. I have tested with Gentoo/Sabayon, System Rescue CD, Slackware, plus a number of others. Most work well with BackTrack5 r3; however, the TP-LINK is unstable for penetration testing. Did not test PowerLink with BT5r3. Alpha is the most sensitive and picks up the most APs. Etekcity picks up almost as many APs as Alpha but is more stable, once it connects to an AP, it doesn't drop the signal. TP-LINK picks up a lot of APs and once it connects, is very stable. Gsky and Generic are just average performers. Power Link is better than Gsky or Generic but not as good as Etekcity. The Engenius antenna gives a noticeable improvement over the antennae that come with the adapters. For example comparing Alpha with its 5 dBi omni antenna and Alfa with the Engenius antenna, I left kismet running over night for both, the 5 dBi antenna resulted in 289 networks spied and the Engenius antenna resulted in 400 networks spied. (I live in a city and there are a lot of APs nearby, I have identified 53 with strong enough signals to attempt a crack. 4 are open with no security; 27 are WEP - 21 cracked, 2 hidden SSID and 4 out of range; 22 WPA - 6 cracked, most of the rest are too old to have WPS so reaver does not work or are out of range, only 1 had WPS turned off. It requires a much stronger signal to crack WPA than it does to crack WEP.) Comparing the Alpha Omni antenna to the Panel antenna, I observed no difference in performance either with signal strength or number of APs spied. I tested all adapters with txpower settings from 50mw to 1000 mw (or max for the adapter). The transmit power has no effect on the number of APs spied, signal strength, or stability of connection. Not surprising since the receiver's sensitivity is unaffected by the transmitted power. Once you have adequate transmit power, the receiver sensitivity is the limiting factor. I just use the 50 mw setting for all of them now, it cuts down on interference. I just got the BilcoWifi Cantenna and have only tested it a little with the TP-LINK, it is very directional. If you point it directly at an AP, there is a dramatic improvement in performance wrt all the other antennae. The signal strength and signal quality that Linux reports for wifi adapters is pretty meaningless. To compare 2 adapters, I use a program called iperf, it is a simple Linux command line tool that tests data transfer speed between a client and server. A tip for using BackTrack: I had problems using airmon-ng and monx interfaces. The following works without problems: ifconfig wlanx down iwconfig wlanx mode monitor ifconfig wlanx up Then just use wlanx instead of monx.