If I understand my Linux-fu correctly, HDA and HDC are not drives. I think they are partitions within drives.

No, /dev/hda and /dev/hdc are drives (master on first and second IDE channel, the MkIIs fake it by playing with the major and minor device numbers - you could create /dev/foobar that points to what's normally referred to as /dev/hda by using the proper numbers when creating it [/dev/foobar]).
/dev/hda1 etc are partitions on the drive (1-4 primary partitions and 5 and up are logical(?) partitions in one of the primary ones. /drive0 and /drive1 are AFAIK just mount points (normal directory entries) on which the main partitions are mounted.

Hope I got that right... If not, I'm sure someone will correct me.

/Michael