I had an issue with Windows 7 not booting once I removed an old hard drive that had Windows XP on it. I had thought this would go seamlessly but apparently my 'System' volume was set to the old drive.
Getting rid of this issue was a pain to say the least.
The windows 7 disk was the first attempt to remove the NTLDR error, even tho it doesnt make sense as that is only need for XP.
Anyways, choosing "STartup repair" and similar from the Windows 7 disk did not fix the problem even though it found items to repair each time.
I ended up fixing the issue after doing two things:
-Disabling the 'Quick Boot' option in the BIOS
-Eventually selecting the system restore option
I find it goofy that this worked, especially since the restore would still be using the old HD in my mind. However, maybe the non-quick boot allowed the system to do a deeper check and not fail instantly on the NTLDR error?
Could be... in either case, this fixed the issues.