[CentOS] Now you did it Olly

> Speaking of that, is there some way to move the grub bootloader to that 
> USB drive so at least I don't have to rebuild that drive too? 

Why, won't dd work?
dd if=/dev/sda of=/dev/sdb bs=512 count=1
is the usual command

But if you're booting from the USB stick, I think that sda and sdb will
be swapped around, so
dd if=/dev/sdb of=/dev/sda bs=512 count=1