The System Health Report is one of the most useful. It takes input from the Performance and Reliability Monitor and turns it into a well-organized, information-packed report that does a good job of spotlighting potential problems. To run this report, open Control Panel, click System and Maintenance, and then click Performance Information and Tools. In the Tasks list along the left, click Advanced tools. The last item on the resulting list is Generate a system health report.
Each report gathers information for roughly 60 seconds, so it's easy to run several reports. To establish a baseline, run a report immediately after startup, with no programs running except those that start up automatically. You can run additional reports while you run particularly stressful programs to see whether the load is overtaxing your system.