None of the above.
I use a generic USB memory module thingy, and you plug in a Compactflash card into it. That way I can update the memory I need much cheaper and the card also doubles as the memory card for my camera, so I don't need to carry the tranfser cable around with me.
You can get Compactflash (and other formats) pretty cheaply now, and they come in up to 2.2 gigs as I write this.