Windows 7 does not have drivers for Xerox Docuprint P8ex
The Xerox DocuPrint P8ex understands PrinterControlLanguage of version 5e or 6 (PCL 5e or PCL 6). So actually you can use driver from every printer supports PCL 6. Driver for "Fuji Xerox AP-II C2200 PCL 6" working very well for me on Windows 7 64bit.
Steps to install:
From Device Manager -> Other devices ->Right click on DocuPrint P8ex -> Update Driver Software -> Browse my computer for driver software -> Let me pick from a list of device drivers on my computer -> Double click Printers -> Fuji Xerox from Manufacturer -> FX AP-II C2200 PCL -> Next