When I was starting with Linux, I had to dual-boot my computer so I have a back-up working OS should Linux fail (fortunately, it never did). Dual-booting means learning how the boot manager works and back then, it was LILO, the Linux Loader. I was such an expert then that when GRUB, the Grand Unified Bootloader, was introduced, I stubbornly stuck with LILO. :)
Today, GRUB is now the more dominant boot-loader so it is high time that I learn it. Fortunately, Chad Files, of Linux.com, provides an inside look at GRUB, how it works and how to tweak it. Of really particular interest is on how to boot from a USB drive using GRUB.
I urge you to check it out and learn how GRUB works. It is an essential knowledge specially when you are helping migrate users from Windows. I wonder if this works with Intel's EFI.