Think you will most likely need a Linux machine and a sniffing program like aircrack (plenty more of them out there).
Depends on what encryption the wi-fi is using as well. @D 8 RCS - depends on your neighbours lol. I wouldn't p*ss on one of my neighbours if they were on fire.
I bought a wifi aerial some years ago for an old laptop wifi card due to a poor signal upstairs. I use to live on a large council estate so when I scanned I found 100's of open wifi/unsecured all within a stones throw off mine. I use to know the local boozers wifi password about 400yard away so I used his wifi for a years.
As for hacking someone's wifi ? I would like to know why you want to do this