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.
There is no way to downgrade from Windows 8 to Windows 7. You will need to conduct a fresh installation of Windows 7. That will require you to buy a copy of Windows 7 (upgrade or full version will work) from a retailer (NewEgg, Amazon, Tiger Direct, Best Buy, etc). The best cost effective solution for you if you do not prefer the Windows 8 standard tile interface (a.k.a. Metro) is to run a 3rd party tool like Start 8 to be able to get a Windows 7-like interface in Windows 8. I hope this advice is helpful in your efforts.
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).