Alfa 500mW AWUS036H USB Wireless Adapter 802.11 b/g Network Radio Card is a win in Backtrack 4!
I picked up a Alfa USB Wireless Adapter about a month or so ago, and it's a definitely a good card for Backtrak 4.
I had to switch the realtek driver for it, and boom, every wireless utility a tried in BT4 worked great.
So to get the good love, follow my simple steps in BT4:
vi /etc/modprobe.d/blacklist
find "blacklist r8187" (if you don't know how to use vi or vim, I weep for you.)
comment that out with the hash / pound / number / whateveryoucallitinyourworld "#", and add this line:
blacklist rtl8187
save it and reboot. (too used to dealing winblows.. probably could remove it and rmmod the rtl8187)
it should be using the r8187 kernel module instead of the rtl8187.
Boom, kismet should work and all the other good stuff should work in BT4 with this good card.
A side item: if you've never used wepbuster to show someone how bad wep is, do it.
Eric and I wrote some scripts for DEFCON a few years ago to automatically crack WEP with the parts that were around then. This does something just like it, but seems to run through all the different vectors you could use. Basically, start it, and let it go... very handy!