You will need linux, ubuntu is preferred, then on your linux type "sudo apt-get install aircrack-ng" without quotes and then use the help file of that tool to read how it works, that is the best wireless hacking tool ever. You will need a wireless card that is compatible with aiopeek driver and atheros chipset is also preferred as it is compatible with both the peek and aireplay ath driver, works well with madwifi driver and has not given me any problems. after you have installed aircrack then you get "sudo apt-get install madwifi" and "sudo apt-get install madwifi-tools" then you will have compatability. read in the aircrack file how to do the rest because there is alot of other small commands you must use before it actually work. Cain can only crack WEP. Aircrack can do both WEP and WPA.