Well, there's a way, but it's rather complicated: run two copies of Media Center on your home PC, the first is the server, the second has a library on the USB drive, and do the library sync. Then run two copies of MC on your laptop, the first is the server accessing the USB drive, the second is with the "good" library syncing to the first.
If you don't do conversion, you are limited to the network speed at home, which should be fast. The big advantage of library sync is that it does all the steps for you.
j