As far as I know some people hooked up SATAe (external SATA) HDD drive and often it even worked, giving them extra space for recordings. I never heard of anybody using USB drive but maybe I missed it somehow. To record on PC you would need firewire, but I don't think too many people were successful, I know it doesn't work on mine, even if it works with my very old Sony cable box. Again, I don't think USB can be used for recording purpose at all. And don't expect hooking up the hard drive to SA box, record some shows and then bring it to computer, they use some proprietary file system and files are probably encrypted, unless somebody broke that as well. There are large threads in DVR section dealing with both issues but I haven't keep track of them lately.