Ahh, well you need to format your USB key so that it is bootable. The USB Storage Format tool can do that.

You can get the tool here: http://www.pcadvisor.co.uk/downloads...4&itemId=64963

Heres a guide on formatting it: http://www.gamebeat.net/forum/showthread.php?t=1057

Put the bios file on there and try it out - get back to me with results.