Lord Chaos,
How old is your PC/Motherboard? What is the make/model of your PC/motherboard?
Most new PC BIOS have the ability to boot from a USB drive. When you turn ON your PC, press the key to enter SETUP - poke around through those settings (be careful not to change anything you don't understand as this can cause bad things to happen). If your BIOS supports this, you should see an option in there to select a USB drive in your boot menu.
Knowing your PC / BIOS version - I could look it up and tell you exactly where to go in the SETUP - provided this is an option on your PC.
Here's a step-by-step guide for booting from a USB drive - I believe it's for Ubuntu Linux.
http://www.aselabs.com/articles.php?id=243
- John