Q: What options do I have for wireless for a power pc G5 to be able to access Airport Extreme??

I just got a new mac pro with airport extreme to handle the wireless needs.  I have an old Power PC G5 1.8 GHz dual processor that I would like to use and have wireless capabilities.  I want to use the airport extreme to access the internet on the power pc G5.  I have an airport utility on the old power pc G5 but when I goto set up the airport utility, it states I do not have a wireless card.  Where do I get a wireless card?  Is there a usb I could hook up to function as a wireless card without needing to get into the computer.  either option is possible, I just do not know how to move forward.  Any help would be appreciated.