The problem may be that Windows 7 will configure the Dual Boot making the previous Windows 7 installation System Active drive holding the MBR, while the new Windows 7 drive will be simply Boot Primary.
Let's make sure the incorrect Active formatting (Partition Magic isn't compatible with Windows 7 64 bit, I believe) which was applied to the new drive is wiped completely clean.
Boot into Windows 7 DVD Repair console, open a Command line and type:
SELECT DISK # (for new Windows 7 HD)
Now boot back into the DVD, select Custom install, use Drive tools to create New partition(s) as you wish, format and install Windows 7 to the first partition on your new drive.
If the error repeats, please note exact wording, then enter BIOS setup to check that the new HD is registering and the exact setting for SATA controller for both drives.