Just got me an Airport Extreme today. Planning to hook up an external hard drive (3.5", externally powered) and a Canon printer to the AEBS. Looking at a USB hubs to hook up multiple devices to the AEBS and I'm slightly confused as to whether I need an externally powered or USB powered hub. Both the hard drive and the printer have their own power sources. I'm guessing the USB hub does not need to be externally powered (i.e. it can be a USB powered hub)??? Thanks.