Altiris documentation site - you'll want to look for Symantec Management Platform and Software Management Solution (pdf format).
Knowledgebase - More for looking up defined errors, however lots of pointers are available. I woud start with the
planning and implementation guide , which also has a link on the side of the article for some best practice links.
You obviously found this site, but a companion site is
Altirigos.com
One thing you may want to look at is where the client is in location to the Notification Server. The package has to be published, and then downloaded. If you don't have a site server, which is an extension of the architecture, you may see download 'problems' depending on how your network is laid out.