Did you try to install the Nvidia driver after removing the device with the 'remove driver' checkbox checked?
There shouldn't be a Sony vendor lock that disallowes nvidia drivers to be installed.
Installing the specific intel drivers did fix some issues on my Viao X, take a look here.
Microsoft will be releasing the Windows 8 Release Preview tomorrow, so you can also wait a bit and install the Release Preview instead of the Consumer preview. Check here for a guide.
Hope this works for you.