That explains why this is not working.
You can download a Windows 7 repair disc from here. This is an official microsoft release, you can get it free using the torrent link but will need to have a torrent client installed like Utorrent. Or, you can get a direct download but you have to pay for that. Download Windows 7 System Recovery Discs — The NeoSmart Files
Once you have this you will be able to go through the instructions I gave earlier. You need to check that the drive is set to Active before trying to repair the MBR. If you still have the old hard drive installed you may find it is still trying to boot from that and the new installation has switched to inactive.