[Cliffy]

On your router, the wireless security is set to WPA shared key, and a key is entered?

The only way to connect to your wi-fi would be to enter the shared key into the devices. If none are asking for a password, are you sure you are connecting to your router?

 

[Cliffy]

but my Mac Mini has built in airport. Can't I just connect directly to that without a router?

You could enable internet sharing and share over wi fi.