Also FYI, The Toshiba Thrive will only read FAT/FAT32 drives. So forget about your 1 Terrabyte Passports or anything over the 320Gigs that FAT32 can format. Also the external drive will either need it's own power supply or have to be able to run off the low power of the thrive's battery support.

All that said, it will support an additional 32Gig's via the SD Card reader slot and any USB Thumb Drive formated to FAT/FAT32.