The Dell SSD is crashing because the Sony uses different drivers. Plus the Dell version of windows is an oem that isn't transferrable to another system and would eventually fail Windows Genuine Advantage checking and bring its own issue to your system.
Put the SSD back in the Dell, sounds like you will be using it for a while more.
As for not losing your stuff on the SSD, where are your backups? It sounds like making backups should be the first thing you should do. I suggest making 2 copies. Then when your SSD dies, your files wont be an issue.
Now you can contact Sony for your Restore disk set; it will be cheaper than buying windows. When you get them - now you can move the SSD to the Vaio, restore the system from those Sony disks, and finally bring in your files from your backups.