tony draper,
See the FAQ at the USB industry association website :
USB.org - FAQ: Cables, Connectors, and Networking
And for those people promoting Active Cables, see the USB Compliance checklist (
http://www.usb.org/developers/compli...khub080205.pdf). Specifically page 3, section 1.1 which I'm not going to reproduce here out of respect for copyright. So called active cables are a no-no.