You're better off for now just using the card by itself. For some reason, there aren't very many Mac drivers for USB wireless network products, no matter who makes them. To me this is kind of dumb, since Apple pioneered the use of USB, but there it is.
You might see if you can get the antenna out of the case and stick it on your iBook for better range, but howardm4 is right; your Beige G3 is SOL.