My computer's OS is Windows XP Media Center Edition, Version 2002, Service Pack 2. There are 2 hard disk drives. C: - total size 19.1GB. D: - 37.2GB. The computer was "fixed" by a friend of my dad's, and I honestly don't think he knew what he was doing. It looks to me like Windows is installed on BOTH drives. I'm not sure, but I don't think that's needed, and that it's a big waste of space. There is a Windows folder on each drive...
So my questions -
Is this necessary?
Can I delete one of the Windows versions?
Which one do I delete, and how?
And if I do this, how do I keep all my programs/files safe? Some are in one drive, and some are in another (MOST are in C: drive, so if I can't save what's in D:, oh well).
I did Start-Run-%windir%, which opened C://WINDOWS, so I'm pretty sure that means that's the one my computer actually uses.

Please help!

Thank you.

Is it 2 hard drives or 2 partitions ??

One way of setting up windows was to create a folder on a different drive or partition and copy the cab files or I386 folder from the disk and install windows from there, this way when installing new hardware it would not ask for the windows disk as it knows in the registry where the cabs/i386 folder is.

Also if you lost or damaged the disk or had to format the C partition you could install windows again without the disk.

To check if it needs the drive to start just disconnect the D drive then start the computer.

Can you tell me what folders are in the windows folder on the D drive.