Macbookpro can't recognize bootable usb at boot time?
rEFIt is a useful utility for selecting boot partitions that don't necessarily show up normally (Linux bootloaders, incomplete installs for example, or if there is something out of sync with the boot sectors).

You could use it here to see if it can recognise your USB stick, you could also use it to boot Windows from FireWire if that's at all useful.

You'll need a second usb stick to run it in 'live boot' mode, if you don't want to have it installed on your system, but it's pretty small so even 20MB is enough. Download the disk image and use Disk Utility to clone it onto your second usb stick, then boot with option held and it will appear.