Hello,
Check these Articles:
Symantec Endpoint Protection support for embedded operating systems
http://www.symantec.com/docs/TECH106027
Instructions for installing Symantec Endpoint Protection on the XP Embedded Operating System
http://www.symantec.com/docs/TECH94839
Installing the SEP 12.1 client on Windows Embedded Standard 7 with File Based Write Filter (FBWF)
http://www.symantec.com/docs/TECH185704
How to Review the Enhanced Write Filter (EWF) or File-Based Write Filter (FBWF) Settings in Windows XP Embedded (XPE)
http://www.symantec.com/docs/TECH94790
Regards,