I would ask why bother? If you do not like metro it is a lot less hassle to just use something like Start 8 and never use the metro interface again. You get a leaner and meaner Windows 7 and no messing with the downgrade.
I had a look at Sony's website, and I see that they only list Windows 8 drivers. Because Windows 7 and 8 are very similar, there is a good chance that the Windows 8 drivers will work under Windows 7. Just make sure to get the correct architecture (x64 or x86).