A) Get soft that extracts windows key. There is no official soft through MS, and only 3rd parties. I have one somewhere too if you can't google it.
B) Either Get WIN7 key and install WIN7 again. You should seek Win 7 Media Creation Tool on MS sites or just any ISO.
C) Upgrade to W10, get the key, download ISO using Media Creation Tool. Do clean install on SSD.
Alternatively just buy Windows it's not super expensive.
I am planning on upgrading to Windows 10 as soon as I sort out migrating Win 7 over to the SSD. I do not want to upgrade to Win 10 first because I want to still have a copy of Win 7 to fall back on in case of problems.
I did run into some issues with the SSD last night. While looking at it in the Win 7 Disk Management utility, there are 5(!) partitions on the SSD (in this order): a 701MB unallocated block, a 400MB "Recovery Partition", a 300MB "EFI System Partition", a 213.53GB RAW Primary Partition (E: Volume), and finally a 23.45GB unallocated partition. I tried to delete the 400MB Recovery Partition on it as the option isn't grayed out, but it comes up with a message saying that the partition wasn't created by windows and might have data from another OS on it. Don't care, click Yes to delete the partition and it says it couldn't be performed because of a device I/O error. Can't delete the 300MB EFI partition as the option is grayed out, Can't delete the RAW primary partition either (or even change it to NTFS). I really don't care too much about the 701MB, 400MB and 300MB partitions existing as those are chump change, but having that 23+GB unallocated chunk at the end is annoying because it's so big and right next to the primary partition (it would be ripe for a merge).
So are these partitions necessary and is there a way to delete them all (or at least merge the 2 unallocated chunks into the primary partition? I assume I need the SSD drive in NTFS format, so is there a way to do this? Windows can't seem to do the format.