You are good up through the SSD install, but you cannot format a boot drive. If you have no extra SATA data and power cables, then once your SSD install is complete and working well you can attach the HDD with those same cables but boot from the installer DVD. Then rather than doing an install go to the command prompt and type:
diskpart
list disk
select disk n (where n is the HDD)
clean
This will result in an unallocated HDD. When you attach it and startup from the SSD (make sure to set the SSD and not the HDD as the boot device), go into disk management and initialize/format the HDD. This would wipe everything from the drive.
If you want to save anything from the HDD, just attach both the SSD and HDD, boot from the SSD, then delete what you want from the HDD (you may have to set the HDD to inactive to delete the Windows folder on it).