Another vote for the PD70X.
I've got a 40GB drive in mine but you can install just about any notebook drive. The PD70X is extraordinarily fast (i.e. just over a minute to download a 1GB CF card), absolutely reliable, and it has excellent battery life.
Sure, you can't preview pictures, rename or edit files etc, but what it does it does very well indeed ...and it's about one-third the price of the Epson device.