The combo 10.4.11 update does that, once installed it will allow WPA but not WPA2 on the original Airport card. Some of the research I've done over the past month, seems to suggest that the original Airport cards are also very picky when it comes to none Apple routers. Apparently some of them handle wifi encryption in a way that the cards dont like. Which can lead to problems like I've been having.
The only solutions are see for Powerbook owners are
A. Go USB and reap the benefits of the extra ports and the WPA2 encryption, thus bringing your machine inline with more modern tech in the house.
B. If keeping your machine original is important to you, find a router that is backwards compatible, that will support WPA encryption in a way that works with your existing Airport cards. Alternatively, use MAC filtering with a hidden hotspot, but be aware that a resourceful nerd can still clone your MAC address and gain access to your network if they have a mind to do so. I keep a close eye on my router and the connected IP addresses, just in case.