Symantec IT Management Suite 7.6 powered by Altiris technology Planning for Implementation Guide
"Symantec recommends at least one task server per Notification Server. After the initial dedicated task server, add additional task servers for every 5,000 to 7,500 endpoints."
http://www.symantec.com/docs/DOC8038
Work on inactive machines one at a time. You'll soon understand why they are inactive.