When I log into XP, my 5 hard drives get mapped C, D, F, X, Y (I believe I somehow set 2 of my drives to be X and Y under XP, and the others are mapped ‘automatically’

When I log in under Win 7, the letters are C, D, F, G, H (automatically).

Had I anticipated having a dual boot system, what’s the best way to ensure the hard drives always have the same letter or name under either boot, so I don’t need to change directory paths for various application programs.