USB drive boot manager

Hi /prog/

I have windows installed to one HDD, and *nix to another. ATM i use the BIOS to switch between drives at boot. This is because I want each drive to remain bootable on its own [eg if i brick one of the two OSes]. Obviously this isn't very efficient.

I'd like to have a boot manager installed on a USB drive to select between which to boot, but I want to avoid doing anything that modifies the drives so that they become unbootable without the USB stick either.

Can you point me in the direction of some software that can do this? I've looked at Plop, YUMI, GRUB and LILO but i'm not really sure which best suits my needs, and if its possible to use them in the way i describe [from USB stick, with USB keyboard and without modifying their MBR etc].

>>28
wow ok thanks, thats a little above my head though; i'm guessing its assembly but i wouldn't know if it were AMD or AT&T, how to compile it or what to do with it afterwards (I sort of assumed the fact that I'm using PCBSD and ubuntu would have hinted at that ;P )