You need to clean install the version of Windows that was on the other ssd, that wasn't in the pc, you're putting it in. Otherwise you'll have serious issue's in that one's version of Windows. Also, if you're putting the ssd that had Windows 8 into another pc, you'll need to clean install both for the dual-boot to work properly. For it to work correctly, you should do a clean/Custom install of Windows 7on the 2nd ssd from inside of Windows 8.