I've recently ran into problems after installing Vista

Hey,
I've recently ran into problems after installing Vista. To cut a long story short, my old hard drive with Windows XP had been dying for a while so I decided to replace it and run a clean install of Windows Vista on the new drive at the same time. Plugging in both hard drives, and setting the new one to slave, I ran the ISO from the XP hard drive using daemon tools and installed. It worked fine until I attempted to disconnect the old hard drive with Windows XP on it and set the new one as the master drive. When that happened, the Vista Boot Loader screen did not show up on booting, despite the drive it was contained in being in the BIOS acknowledged as the primary master drive and it being assigned as drive C:. Instead I receive the error:
NTLDR is missing
Press CTRL + ALT + DEL to restart
Can anyone help to solve this problem? I have since plugged back in the hard drive and can run both XP and Vista for troubleshooting. Any help would be appreciated.