WinPE 4.0 Driver Compatability

I am in a situation where I need, some might say finally, to upgrade my PE environment from 2.1 to 4.0.  The downside is the environment has a lot of older hardware models and I do have some concern about driver compatibility.  I understand that Vista drivers will generally work with Windows 8, does the same hold true for WinPE?  I am certain there will be exceptions but a general answer will suffice for now.

Thanks in advance!