Yes you can, my Pioneer 600AV as well as my Xtreme and Ace full DVD players and my Coby portable player which are all equipped with usb function and Divx capable can detect a 500G(it's hard to format a 1Tb FAT32, but if you can do that, it will be detected) HDD as long as it's has it's own power supply(3.5") and most importantly was formatted to FAT32.
Per my experience, only my Coby portable can detect a 2.5 320G(pqi only, but not seagate or WD brands) usb powered HDD, but with limitations to only two 700mb movies.