Wayne Stallwood wrote:
b) How to (e.g.) wipe that other OS off the drive and install Linux without affecting this hidden partition?
This would probably be easiest if you select to manually configure your disk partitions as part of your Linux installation - most installers I have seen will use the whole disk by default - ymmv. You may want to look at something to take a copy of that partition before performing your install if you are concerned - I have used g4u (http://www.feyrer.de/g4u/) successfully in the past to take a copy of a Dell Diagnostics partition before clearing a drive.
When you use fdisk (or similar) if it exists it will appear either as an unidentified partition or maybe as a small FAT partition. It's not actually hidden as such it's just in the first case Windows won't assign a drive letter to a partition it doesn't know how to read and in the second case they have probably adjusted the Windows installation to not assign a drive letter to the (otherwise standard) partition.
If you are really nervous you could take a look from the windows (NT, 2000 or XP) installation by punching services.msc into the start menu run box (or right clicking my computer and selecting "manage") From the management console you could navigate to disk management and look at the partition layout of the disk (including any unidentified or unassigned partitions)
You will probably find that services.msc will not show you what Wayne expects here - its loosely an M$ equivalent of nix 'ps ax'.
Try entering compmgmt.msc to display the equivalent of Manage from the My Computer menu. If you just want an equivalent of cfdisk (or probably closer to qtparted) enter diskmgmt.msc at the Start and Run prompt. You may have to be using an administrator account on the windows machine - can't remember.
If such a partition exists it will be apparent in fdisk regardless of it's type.
HTH,
Jim