Hi Sherry,
I don't think officially, the iPad can use external HD's - though some do appear to work using the camera connection kit.
However, of course, you can sync the iPad to a computer using iTunes... which acts as the perfect hard drive.
I'll have to find out if you can copy from the iPad to an SD card in the camera connection kit or not...
You can find out more info about it here:
http://store.apple.com/us/product/MC531ZM/A?mco=MTY3ODQ5OTY#overview
:)
Rounik