Looks like our very own Bhaskar Krishnan has written a great post on troubleshooting some of the frequently encountered issues relating to client content download problems in System Center Configuration Manager 2007. It outlines the scenario, then takes you through how to track the various processes involved from when the client downloads policy to when the client installs the software, such as:
If you haven't had a chance to read through this yet then you'll definitely want to put it on your to-do list:
http://blogs.technet.com/configmgrteam/archive/2010/01/14/troubleshooting-client-content-download-in-configuration-manager-2007.aspx
J.C. Hornbeck | System Center Knowledge Engineer