Hello,
Since you are new with "Symantec Endpoint Protection 11.x"
Please Follow this Article on Fresh Installation of Symantec Endpoint Protection Manager (SEPM) on the XP machine.
Installing and configuring Symantec Endpoint Protection 11.0 for the first time
It is always recommended when Installing SEPM on the Server carrying XP Operating System, you visit this Article first:
Best practices guide for installing the Symantec Endpoint Protection Manager (SEPM) on a Windows XP operating system.
http://www.symantec.com/docs/TECH91694
http://support.microsoft.com/kb/314882
Again, What Service Pack is installed on XP Pro machine?
Microsoft has officially retired XP SP2. http://support.microsoft.com/lifecycle/?LN=en-gb&C2=1173
To remain secure, I would recommend that all XP systems be upgraded to SP3 and all the latest patches applied!
Hope that helps!!