Easiest and least risky way to render an NTFS volume non-bootable?

Factual Questions
1

It might seem a bit oxymoronic to be asking about the least risky way to render a drive non-bootable, so let me explain:

While my sister was on holiday, I took charge (at her request) of her computer, removed the 40GB hard drive in it, replaced it with a 120GB drive and performed a clean install of XP home and various other bits of software. Then I installed the old 40GB drive on the other IDE channel, so she would still be able to get any files she wanted.

All was peachy; the new installation is great and there’s a significant improvement in performance. Until today, when for some reason, the POST informs her that the drive configuration has changed and that this affects the boot sequence - and the machine attempts to boot from the old 40GB drive instead (which almost works, but wouldn’t be what we wanted in any case).
So I popped over and edited the CMOS settings to restore the proper boot sequence (removing all reference to the 40GB drive in the list of devices to try booting from) and all is peachy again.
Except that I’m not entirely convinced that some kind of POST glitch won’t do the same thing again - so I’d like to render the 40GB drive non-bootable without destroying any of the the data on it.

Anybody know of a way to do this?

2

Why don’t you just snag her files off the old drive, then disconnect it?

If you don’t ever want to boot from it, you could remove the whole \WINNT (or whatever) directory. You may also be able to use fdisk to make it non-bootable.

3

  1. Use a partition management program to make the boot partition hidden on the 40G. Use XP computer management to assign it a drive letter. It won’t boot if the 120G fails to and when the 120G boots it will be able to read the drive. The 40G Boot Sector will tell the bios boot code that the partition is hidden and can’t be used to boot. The XP can handle that condition after it boots.

  2. You can copy the files from the 40G to the 120G and format the 40G. Transfer only the data files back to the 40G, and you gain back a little more storage.

  3. The messiest solution is to delete the XP critical to boot files from the 40G. I would recomend one of the first two methods.

4

Since you don’t say whether or not the computer was rebooted after installing the old (40 GB) drive and assuming you hadn’t rebooted, did you reset, or set, the correct slave/master jumpers on both the drives?