Also, is the security in these things adequate?

By default, probably not. A neighbor with an 802.11b card could probably hang around on your network.

In our town, we have an internet service provider who has an 802.11b network in their central office. This is not my provider, it's my provider's competitor.

Well, the owner of my provider's company, Scott, likes to take his laptop with him when he has lunch at Burger King. See, Burger King is next door to this competing ISP's office, and Scott can surf the net using their 802.11b router.

Scott, on the other hand, builds little custom 802.11b routers using his own custom-modified Debian distro running from flash RAM. He locks everything down so that others cannot do what he does at Burger King.

One of his tricks is to lock out all MAC addresses except the ones he specifies. So only a given set of cards will be able to access the router. I don't know if that would be possible to do on the off-the-shelf routers, but if it is, that would be adequate security for your home LAN, I think.