The Overdrive has a microSD card slot that you can use for file storage. You can access the storage by mapping a network drive on your computer. Unlike an actual card slot that is built into the computer, the computer would require the mapping of the drive since it is connecting to the Overdrive through the WiFi network it creates. The exact steps are listed in the users manual forthe Overdrive step by step.
And the really cool thing is this 16GB drive can be shared between all computers connected to the Overdrive - it's not limited to just one computer. Any computer connected to the Overdrive can access the network shared drive.