Vista Drivers - 71.sp2 - options

All machines we use are lenovo. Fortuntaley we have been able to boot to PXE in all models so far. Now we have a new X240 that does not have Vista drivers.

I assume  the only options open to me are upgrade to 7.5 or upgrade to WinPE4.0 in current setup.?

If I upgrade to 7.5 will it retain the driver database or do I need to reimport for all models?