It sounds like you correctly unplugged the HD when installing to SSD. If you're receiving boot errors after plugging back in the HD it might be that you deleted Windows 7 from it and BIOS is trying to boot HD first.
Set SSD first drive to boot in BIOS setup. Then if you need to boot the OS on HD use the one-time BIOS Boot Menu key, or when ready move the data off and delete the HD Windows partition which is the correct way to delete an OS.
If probs persist post back a screenshot
of maximized Disk Mgmt drive map and listings, using Snipping Tool in Start Menu. If you can't boot to do this then post back a camera snap of free Partition Wizard
bootable CD drive map and listings.