I think I have an idea on how to do this, but I'm not entirely sure.
I've got a WHS setup, but I'd like the ability to plug in a HDD (containing a win 7 install) and it automatically boot from that disk whenever it's plugged in. I have a HP MicroServer and if I set the disk to be boot priority 1 in the BIOS and then subsequently remove it, the next time it's inserted it will be the lowest priority.
However, the USB ports always have top priority, so I was thinking of being able to simply plug in a USB memory pen at the same time as when I plug my Win 7 install in - and that having a bootloader on there that is preconfigured to boot that specific HDD.
Am I right in thinking I need to use something like GRUB on the USB stick, and set it up as such so it looks for that specific disk's identifier?