The ISA Server developers did not disappoint when it came to developing the monitoring and troubleshooting tools made available to administrators. Using advanced logging to an MSDE or SQL database allows for advanced report generation, fast indexing and searching, and real-time logging. ISA Alerts, Connectivity Verifiers, Session Monitoring, and the ISA Dashboard also provide for excellent "out of the box" monitoring functionality.
In addition to monitoring with the ISA tools, Microsoft Operations Manager (MOM) 2005 can allow for proactive management and troubleshooting capabilities in an ISA Server environment.