If you already have a router, there's an additional option that doesn't require a crossover cable: Windows Easy Transfer. It comes with Win7 and the XP version can be downloaded free from Microsoft. You cable each box to the router, run WET on each one, and follow the prompts. Not sure it's any faster than USB to USB, but it's mighty convenient.

Caveat: it can't be used to transfer an *installed* program - ie. one with registry entries. It's intended for data file transfer. But since BB doesn't use the registry, I believe even it can be transferred this way and still execute.

FWIW.