I have an iMac G5, Rev. A that has 3 USB ports in the back. I want to add a few more because it is awkward plugging any more USB devices (such as my flash drive). Is there a cable or something that will allow me to have multiple USB ports? I plan to upgrade to Leopard when it shows up, so maybe there is an external hard drive I can buy that will have extra USB ports. Thanks for your help!