Erm, I was going to come here and ask for advice, but looks like I may be able to offer some instead.
I have a G4 800, running Tiger and have just got a Belkin F5D7000 running with the drivers from this site. It's running WPA-PSK with no problems at all and I *don't* have to enter the key every time.
First of all: The /System/Library/Startup Items/WiUtilitySetup folder is incorrectly named. It should be called 'WiUtilityCardbusSetup' or similar - ie. exactly the same as the executable inside it. I also found that the permissions were nonsense - the directory, and both executables inside it should have rwxr-xr-x permissions, with root:wheel ownership (chmod and chown will sort that). The startup plist needs to have r-wr--r-- permissions with root:wheel ownership again. Sort these and the utility will fire up on system startup (it still takes it's time though).
For automatic connection, select the relevant access point and then 'create profile'. Set all the options in the profile as required (including WEP/WPA keys) and save it. Then select the profile and click 'activate'.
Assuming you've done everything right, this should now automatically connect on startup every time. As I said, however, it's not fast. I've had to disable a couple of startup items that need to access the net, as it's a good 20-30 seconds after boot before the utility appears.
Now, if only I could find a way to *not* have the utility appear and just silently connect in the background...
