Going slightly off subject ....
I believe your correct with the statement about the mem card, but I had a look at the 007 exploit with a Hexeditor. The called XBE was pretty easy to spot as "d:\UDATA\4541000d\000000000000\default.xbe"
So I know that the memory cards don't have a logical drive assigned by the bios (I tried some options from H: to W:, but is there a physical location descriptor for the memory cards that could be substituted ... e.g. "\Device\MU1A\dash\default.xbe"
P.S. I know the example above doesn't work, but as the knowledge of the Xbox has grown over the years, has anyone come across a way of directly addressing a memory card in this way???