On your system, I see two hard drives. One shows as one large partition and has an Install on it, Legacy. When I say clean, I mean all partitions have to be removed prior to converting the drive to MBR, IF that drive was GPT to start with.
The other one is showing offline and unallocated. Be careful with this one. If it had been a UEFI/GPT partitioned drive you may be able to recover prior partitions. Having two drives the same size can cause confusion as to which one is which.
I would suggest you download and create the bootable CD for Partition Wizard. Then boot to that and see if it can see any partitions on the drive.
Disconnecting the other drive would be a very good idea. If Partition Wizard sees partitions, you...