how can I boot sl54 from external hd?

[Francis Ogula]

Hello all, I have just installed SL54 on my  transcend external 235 GB
hardrive.My internal hd has windows xp. However, My PC bios cannot boot from
USB. I installed grub to the mbr but it was unable to boot either the linux
or windows OS. I tried installing grub on the external hd linux partition
and attemped to boot it on a hp laptop whose BIOS does support usb booting,
but it only went as far as GRUB_. Is it really possible to boot SL from an
external HD? any help will be appreciated