I would like to download the info on an old extermal hard drive. when plugging the iomega into my mac book pro - it says that USB devices disabled due to to much power to re-enable USB devices ... this hard drive works with the original desktop apple (old computer)

Some older external hard drives required special USB cables with two plug-ins. This was not for the sake of data transfer, but because they needed more power than a single USB port could provide. Some older units even went so far as to have the laptop-type "brick" power supply since they needed so much power. This is probably what is wrong here. Your Mac Book probably doesn't have the current to handle the drive on the port and is protecting itself. Some units have one or two high-power USB ports. This may work if you have one. Otherwise, you'll need to download the drive another way.