How to update norton antivirus

I have a small network with around 100 computers. I have Norton Antivirus Corp. 8.1 and have problems updating it. I don’t want to give our end users local admin privs. According to symantec you need power user or admin privs to update the virus definitions. I have all windows xp desktop and windows 2003 servers. Is there another way to accomplish this? Any help would be appreciated.