Altiris Report to find any Computers not logged into in the last 90 days

I am new to Altiris and I am not sure if there is something out of the box for this. I have a situation where machines will remain on  the network but not get logged into for long periods of time. We want to find the PCs and retire them. The reports I have found look like they only fine machines in Altiris who are offline. Let me know if there is a way to do this. I tried creating a SQL report but the fields are confusing.