AGVictor,
You can use the Active Directory Import tool to import the desired users.
Navigate to Actions->Discover->Import Active Directory.
Create a new User import rule. Make sure that you select the checkbox for "
If you have AD groups that correspond to each department, you can select those as the items to import. If not, you may want to select the AD OU containing all user accounts. Be sure that you've included the department field in your column mappings. That is what will associate the users (and their departments) to their computers (based on the primary user data that is collected by Altiris inventory).
The filters that are created as a result of your AD import are located here: Manage -> Filters - Notification Server Filters -> Directory Filters. If you have imported departmental groups from AD, you can use these filters as-is. If you've imported your users (and included their department information in your column mappings), you'll have to build out your own filters for each department using the imported user/department data.
I hope this points you in the right direction! I'm sure that the AD Import is well-documented.
Good luck!