Whether you keep your old OS on HD is up to you. We can show you how to boot it or delete it..
Did you remove the old HD when you installed Windows 7 to SSD? If so, then it should remain bootable on its own if the 100mb SysReserved or Windows 7 partition was and remains marked System Active.
Confirm that HD has lost its boot by setting it to boot first in BIOS. If it bluescreens again, unplug all other drives, set old Windows 7 HD as first to boot in BIOS setup, boot the Windows 7 DVD Repair console or Repair CD to confirm that the 100mb System Reserved partition or (if you don't have it) Windows 7 Partition is marked Active: Partition - Mark as Active
Then boot back in to accept any offered Repair, if Windows 7 doesn't start or no Repair offered, click through to Recov tools list to run Startup Repair up to 3 separate times to start Windows 7. Startup Repair - Run 3 Separate Times
Once Windows 7 starts on HD, power down to plug back in SSD, set it first to boot in BIOS setup, then boot HD if needed using one-time BIOS Boot Menu key.