This is one of those things where I learned everything I could about my own wireless system, a Linksys, but cannot say it overlaps to others. Linksys provides a website, with a numerical site name, where, after you have connected the wireless, you go in and set everything up. And they take you through somewhat well. From the intial set-up page you go the wireless set-up page and there is a basic setting page and a wireless security setting page. On the basic setting page is an entry that says "Wireless SSID Broadcast" and you can enter enable or disable. (You also enter the wireless channel you want to use on that page.) Enable means your wireless will broadcast its identity, disable means it won't.
However, you don't want to do that "disable" until after you have set up your security on the wireless security page which has WEP (easy to set-up and decent) or WPA (more difficult but tight security) and have all the computers you want to be recognized sign in with the password you have set up for the system. You set up WEP, for example, give it a password in "Key 1" and, amazingly, not in the "passphrase" box you will see on that page which you leave blank (the computer geniuses who make these things apparently like to play jokes), Then when you are done, you go to all computers you want to use the wireless; they will recognize the wireless and insist on a password for the computer to enter, and you put the one in that you set up (and it needs to be something others in the house can remember because they will need it whenever, as computers occassionally do, the Bill Gates masterpeice of a system decides it is not going to do anything anymore and you have to go in and re-enter the password to get wireless. Once you have them all set up, you can then go back to the set-up site and disable "Wireless SSID Broadcast." Your computers will still get wireless but the identity of your wireless will not show up anywhere. Disabling broadcast assures your neighbors won't see your wireless idenitfied and setting up WEP or WPA security assures they won't use your wireless. Note, if you have the ipod Touch (which came out late last year) and use it around the house to go on the internet, you have to leave your SSID broadcast on. The Touch is, as far as I am aware, the first computerized device to be sold generally to the public that was specifically designed to provide internet access only by the user's stealing any wireless signals nearby and as long as someone's system is broadcasting identity and has no security (the Touch recognizes your secured sytem at home and gets in once you have you have sync'd the ipod with your home computer), you can use the Touch to get on the internet by using their wireless.