Brilliant! I forget offhand which buttons flip between different screenshots inside the rom chooser, but this is an excellent way to be able to see a box cover, screenshot and title screen quite handily.
The file folder naming is truly a pain in the cheeks though.
I'd think that someone skilled in the arts of programming could easily whip up a program that compares a .png to a .rom, and if both exist, it just makes a xbox compatible folder, moves the png into it and renames it.
It can almost be done via batch file:
if exist "%1".png md "%1"
if exist "%1".png move "%1".png "%1"\0001.png
Call that batch file recursively with a list of the .ROMs in the folder and you're almost there...