I could have missed this, but I didn't see any mention of the fact that not all BIOS offer booting from a USB device as an option.
Here's another way to go about this...How to Create a PLoP Boot Manager CD
PLoP Boot manager, and extract the files from the Zip to your Desktop.
· Burn the plpbt.iso to a CD using your favorite CD/DVD burning software.
· Insert your Newly created PLoP Boot CD
and your USB Flash Drive.
· Reboot your PC and set your System BIOS to boot from the CD.
If all goes as planned, you should now be presented with an alternate Boot Manager that can be used to boot your USB Flash Drive or other device.
Note: In some cases the Flash Drive will actually appear as a hard disk.
These instructions are found at this site