Ive been thinking . ..
And I think its just the nature of DOS/Win9x and the primary/extended partitioning system . . .
All the primaries are listed first, then all the extended partitions . .. . . Thats just the way it is.
I know you can change it on WinNT/2k/XP and such, but they use a POSIX-like approach at the OS level to talk to drives, so they can assign any letter they want to any drive . . .