Well, they've gone back to that. But not so on XP. I had W7 on a desktop multi-booting with XP. W7 thought XP was on D: but when booted XP saw itself as on H:When you dual boot, the drive you boot into is always the C:\ drive.
But in any case it's an anachronism that has to go. Maybe they should consider everything a network share and use UNC notation. I don't know the answer. But global search and replace of drive letters in the Registry ain't it.