Thanks nagu.

I'll admit I've not got too much time right now, but I've had a read through that and it's not telling me anything there that I haven't already tried.

I'm a little confused as to what I should be able to expect and what I shouldn't.

Should both my hard drives appear at the Darwin boot prompt? Currently only disk0s2 (my OS X) drive/partition is listed. I've tried using fdisk -e to make my Vista partition active (disk1s1), but it still doesn't list it. Should it?

It would be nice if the Darwin bootloader is all I need

I did also previously try copying chain0 over to the root of the vista partition and then editing the Vista boot menu but that didn't work either, failing with the chain boot error message. I did have the drives physically plugged in the other way round then though (OSX was 1, Vista was 0). It's currently OSX=0, Vista=1 and OS X is the OS that boots.