Will have a look at this problem when more awake ;-)
Did you have another thread on this? if so can you post the link to it please.
Amber light on D could be a loose cable/connection.
In meantime can tell you that my Dimension HDD lists these partitions
Partition, Fat (EISA Configuration), 47 MB <<I presume this is my menu for Diagnostics, Restore etc when I Press F12>>
Partition, Fat32, Healthy(Unknown Partition) 4.63 GB <<this is my Dell XP Hidden restore image>>
(C:) Partition, NTFS Healthy (System) 144.32 GB <<this is my XP SP3 op sys and my documents data>>
I only have one Harddrive installed.
A few months back when I had a nasty I restored my C: Partition from an Acronis Image I had on external HDD.
Dell Dimension 4550 Series, Manual .pdf click here