Windows 7 won't co-operate with you when you move it from one motherboard to a different one. It simply will not boot when you do that.
If you want to run Windows 7 on your new Vaio, you will have to wipe the SSD and install a fresh copy of Windows 7 on it from a Microsoft DVD.
However, you should first check that Windows 7 drivers are available for your new Vaio model - don't take it for granted that they are. Check the Sony website that serves your country: http://www.sony.net/SonyInfo/Support/