Patric, don't hijack other threads -- it creates confusion.
There are a couple of ways to secure a network. Access List includes only users whose wireless adapter's MAC ID has been included on an admission list. But requires maintenance of the router each time you have a new user. It's also not very secure because it's possible to fake a MAC ID and trespass.
Better (as it sounds like your tech has) to set up wireless security and give out the passphrase to all the users (with a strict rule about not passing it on).
The penalty is that the passphrase can be quite complicated -- indeed if the tech has used WEP the passphrase will be a string of meaningless HEX code. If possible, change security to WPA as this uses intelligible alphanumeric names and is actually more secure.