How can I see the users and times they logged in and off of a machine using Altiris NS?
You can view the information for user logon by drilling down into the computer via the Resource Manager.
Find the computer that you want to gather the information from under the Resource Tab collections or a report showing the computer. Then right click on that machine and select Resource Manager, then - Events - Computer Events - AeX Client LogOn.
The user logon events will provide you with the logon time, duration and log off.