This is probably the 100th question regarding a downgrade to Windows 7. I just bought a Sony VAIO SVS13122CXB and it came stocked with Windows 8.
I disabled the Secure Boot feature from the BIOS and when I try to boot Windows 7 from the USB stick it just goes on and off where the VAIO start-up logo is. Once I unplug the USB stick it boots to Windows 8 again.
8 really isn't bad at all. I've been using it on my gaming pc since october and have almost no issues with it. Just install a start button replacement like Start8 and I guarantee that you'll never care about switching back to 7. With Start8 I never have to see the Metro tiled start menu and there is no difference (that I can tell) between 8 and 7.
As for how to downgrade to 7, I have no knowledge or experience on the subject.
Windows 8 is actually a very good OS. Every thing you could do with Windows 7 you can do with Windows only faster and easier. Give it five minutes and that is all it takes to navigate Windows 8 like a pro. As far as downgrading I would not know since I would not want to degrade my OS by downgrading back to Windows 7 my hardware needs the best OS there is and that is Windows 8.
Stardock has a program now that will skip the metro interface on the boot and take you straight to the desktop just like the classic windows which you have missed.
PLUS....it gives you your 'START' button back!
With this feature I don't see why you would want to go back to Windows 7 when you can have the same classic windows interface with a much faster boot time.
That is exactly what I use and the boot times on 8 compared to 7 are amazing. My Asus laptop running 7 boots in around 2-3 mins while my pc running on 8 boot in around 30-45 secs without an SSD! In a couple weeks I'll upgrade my laptop to 8 pro.