Thought I would pass along some info I had to figure out the hard way.

It appears Symantec has changed the manual way of updating the AV Parent Server on version 8.1. In the past we downloaded the updated definitions from their FTP, ran the Intelligent Updater, and from there, the server pushed it out to the clients. (For some stupid reason, LiveUpdate is not allowed on our corporate network.) This has worked fine since at least version 7.5. After upgrading to 8.1 I began to notice none of our clients were getting the lastest defs. Finally, after some posts on symantec they offered a solution... they changed the way it updates and it is now necessary to download a XDB file before the server can push the defs to the server. Not sure if I have to do this every time, and have posted another question asking this. For those interested, below is the link to the Symantec posts (you may have to copy and paste the link).

http://servicenews.symantec.com/cgi-bin/displayArticle.cgi?article=16388&group=symantec.support.network.sav.general&mini_version=sav_8_ce&product=sav_ce&product_name=Symantec+AntiV irus+Corporate+Edition&submit=Post&tpre=ep&version_name=8.x&