I tend to try to keep things clean and simple.
The cleanest way to glomp onto free municipal wireless is to install an Ethernet converter and antenna that connects to a wireless router in your home. Your notebook PC is unencumbered by yet another device to deal with. Visitors to your house can use your wireless network. You aren't dealing with specialized extension cables that cost $20-25 each, you're using $3 CAT5 cable. If you later decide to get a DSL or cable modem, you can route the Ethernet signal into the wireless router.