Go in to your BIOS and shut down one of the hard drives and see which installation fails to boot and you will have your answer. Also if you wait for the the "timeout" which is 30 seconds you will boot in to the first entry in your file. If that is the one you want to keep then you're golden. You could also change your boot.ini timeout to 1 so you don't have to deal with the screen. You could also change the WINDOWS="Xp.. 2" so you can distinguish between the two.

Will one of those solutions work?

You could also power off your machine and unplug one of the drives.

It's been a while since I looked at this. I'll skip the 'irrelevant' items.

• rdisk should be the BIOS disk drive ID, counting from zero (0).
• partition should be the partition number, counting from one (1).

So according to your boot file above, rdisk(0)partition(2) sounds like the second partition on your first (C) hard drive, and rdisk(1)partition(1) sounds like the first partition on your second (D) drive.

Now you should be able to follow sknake's advice to disable the second drive in the BIOS (or power down and just unplug the drive) and to change the upper entry to read '2nd ...'. If you then get a boot error when booting from the upper entry while the lower entry boots, you'll then know how those boot.ini entries relate to your drives. On the other hand, if you can boot from the upper entry but get an error from the lower entry, you know that what appears to be the second drive in the BIOS is really your 'C' drive.

BIOSen don't always play nice with their owners. They sometimes name/number drives seemingly at random, something I've always found to be very annoying. (Seemingly, because it's not the order indicated by the manual or the mainboard labelling. 'Puters usually do stuff the same way every time, barring serious hardware troubles.)

Many thanks Sknake and Fest3er. Have added to each of your reputations. Acting on what I see as the simplest from what you said, I changed the first listed system in the boot.ini adding a "1" in there. Then during rebooting noted that the text in the choice of operating system had changed to include the "1". I started the other one and it is the one I want. So now I know which line I don't want, i.e. the one with the "1" in it. See copy of boot.ini again below;
[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(1)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(1)partition(1)\WINDOWS="Microsoft Windows 1 XP Professional" /noexecute=optin /fastdetect
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect

However, I haven't deleted it yet as I wonder as follows;
The default shows the one I am going to delete, which is the second of the installations in terms of time when installed. Now this raises the question, how was the boot.ini written before I installed the second system? Obviously the act of installing a second system makes the boot.ini change. Certainly before I installed the second system, the default could not have been as it is now, as that system was not present. Would there have been a default as there would only have been the one system? Is it good practice to just delete the line for the system that is to be removed? It seems the ideal would be that if I had a copy of the original boot.ini I could just replace the present one with the old one? Or does anyone advise any additional change to the boot.ini? If anyone has a Windows XP with only one operating system can I see a copy of their boot.ini?

Here is my boot.ini:

Windows probably noticed a second operating system and adjusted your boot.ini. Microsoft usually does things like that to make it easier rather than explaining to an end user how to modify their boot.ini file. You can go ahead and delete the line in the boot.ini file its not a big deal to change. Even if you delete both lines and can no longer boot in to windows you can pop in your XP installation CD and launch the recovery console which will mount the drives and you can edit the files from the command line to fix it.

Thanks again Sknake for your quick reply and copy of your boot.ini. This makes me think that in mine I should change it to read as follows;

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(2)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect

Note I changed the default line as well - so do you think that looks OK?

The reason I'm so hesitant and keen to get this right first time is that my PC is from MESH, who include in their installation, a so-called recovery partition (which is the one in front of their original Windows installation in Drive C), and MESH do not supply a straight original copy of Microsoft Windows XP, they include a disc with their logo on which has other stuff in there and they say we are not to use it unless we phone them. Of course I have tried it (in an attempt to solve a problem I had), and that is what resulted in the second installation of Windows that I am now trying to remove. At the time I thought it was re-installing Windows on top of the original - which might also have been a bad idea of course!
The original problem was a Black Screen on start-up. I spent three days in Safe Mode trying to sort that before clutching at the straw that had caused the problem. I had shut down the PC with an HP P1000 inkjet printer still running, and I had switched the printer off before switching the PC back on. (In the past as any printing I had done had not been at the end of my use of the PC, I had switched the printer off long before I switched off the PC) When I tried switching the printer on again before starting the PC it started as normal (but with the extra operating system).
I intend to post this separately as a warning to anyone getting the Black Screen. (If similar has not already been posted)

It looks good to me

Hi Scott,

Thanks again - have altered as I said and you thought looked good - and indeed it is good, the second op system has disappeared. Have also now deleted all the files installed by Windows on that day in question, except I can't delete the My Documents and sub folder created for that installation. Any ideas on that?

In all fairness to the posters who have been helping you out -- you should mark this thread as solved and create a new thread because the topic has changed