Dual Booting Linux and vista
 

i already had vista installed on my sony vaio laptop hard drive. i then installed linux successfully on my external hard drive. my question is how the hell do i boot linux?

I'm wonderin' that too.

Assuming you can boot Linux by changing the boot priority in the BIOS, you should be able to load Linux with GRUB installed on the external hard drive.

I assume you will also want to load Vista (although I have no idea why). To do this, keep the GRUB drive as the boot drive in the BIOS and add something like this to grub.conf:

rootnoverify (hd1,0)
makeactive
map (hd0) (hd1)
map (hd1) (hd0)
chainloader +1