The MacBooks have ridiculously good antennas though, I'm picking up 3x the number of wireless networks that any other computer in the same area is getting, and I can connect to most of them too! Hell, in fact sometimes the list of wireless networks is so huge there's a scrollable list of them
/. is the worst place for legal advice. However, IANAL, but wireless networks are a semi gray area, as in if you don't do anything but connect to the network it's the maintainer's bloody stupidity and fault for doing so, it's just illegal to be h4x0ring it so you can connect to a base station with added security (i.e. WPA/WEP, etc.).
If you seriously insist on keeping others out, MAC filtering and WPA/WEP are utterly useless alone or with dumbarsed passwords that can be bruteforced except to keep out the nub scriptkiddies. If you're that paranoid, just go wired, it's so much harder to gain access to a wired network..