It's not quite true that you can "only" transfer files to the memory card. Using the USB cable and using the 770 as a glorified card reader, correct. (This is certainly the easiest if it does what you want)

However other options for transferring files include Bluetooth (more theoretically at the moment: I couldn't get it to work with Windows) or wireless LAN (scp, NFS, web, ftp).

Cheers,

Andrew