[Puke]

You are correct that the wireless device is the combination of a wireless NIC and a base station, that interface to your network. It is also correct that this opens up what can be thought of as an additional wireless network, that anyone may access.

Listen to Jack, he knows what hes talking about. MAC authentication does not do squat against a determined attacker. Newer wireless devices that support protocols other than 802.11b often have the option to use time based key protocols, that shuffle their authentication keys every few seconds (like most good IPSEC implementations). One example of such a protocol is TKIP. There are a handfull of them, mostly manufacturer specific, that each have their ups and downs.

Regarding range, regardless of the range of the base station, people can access from miles away using sensitive recievers and strong transmitters. Range cant save you, as such things can be made on the cheap with radioshack electronics and pringles cans.

Unfortuneatly, there are no easy answers for home wireless Users. there are more detailed answers for companies that have the time and money to spend protecting their network, but those solutions are largely outside of most peoples means. in terms of effort vs reward, if not in terms of money.

personal firewall software is ubiquitious these days, and that should be "good enough" to protect your home PCs. if you take the best security precautions that you are able, you will probably discourage most casual intruders. which is probalby good enough.