Paul,

You can buy an image tank to transfer your images, they aren't that expensive and can have 40G drives in them, that is some serious storage and is about the sixe of a small tape recorder. The one I have X-Drive Pro also has its own small case which you can attach to your belt and storage for more CF cards as well. Worked well for me at my daughters Communion, as I only had 256meg Cards at the time.

Yes transfer times are a little slow, but if you have two cards you can be transferring from one card while still taking images to the other card.