Windows 7 - Changing from Multiboot to single boot. Can't remove old HD

A while ago I bought some new big 1TB HD's and decided to install windows 7 Ultimate onto one of them. To make the transition from XP to 7 easier for me I decided to do a multiboot so i could switch back to XP if i needed something.

Once i had everything the way i wanted it and i was no longer using XP i decided to remove the old HD. Also it was an IDE and it was cluttering up the inside of my computer. Now whenever I unplug the original HD i get a boot disk failure.

my guess is that my computer is looking to the C drive for where to boot windows 7 but I dont know how to change it so that it looks to that HD instead. If someone could give me some advice on this subject i would be grateful. I'm hoping that I can solve this with software or commands.

This document might assist you in changing the way your PC looks for Windows...I know it has helped me when I've changed from dual boot configs or otherwise messed up boot configs.

Please note you don't have to follow the recovery steps if you are able to boot, if you are able to boot simply boot into safe mode with command prompt and then execute the commands.

How to use the Bootrec.exe tool in the Windows Recovery Environment to troubleshoot and repair startup issues in Windows

You will probably be most interested in the /scanos command. I hope this helps you accomplish your task

What has happened is that the files that Windows 7 needs to start were installed on that XP drive. You need to repair the Windows 7 installation to be able to boot on its own. This is done by running Startup Repair from your Windows 7 installation disk. You may need to run it 3 or 4 times to get everything to where it needs to be.

Remove the old XP drive and then boot the computer with the Windows 7 installation disk in the DVD drive to start the repair.

Startup Repair

Startup Repair - Run 3 Separate Times