From what I’ve read, the Troubleshooting Assistant seems to combine the Microsoft Exchange Server Performance Troubleshooting Analyzer Tool and the Microsoft Exchange Server Disaster Recovery Analyzer Tool, which make-up the Microsoft Exchange Server Analyzer Tools suite <http://www.microsoft.com/technet/prodtechnol/exchange/downloads/2003/analyzers/default.mspx>:
* The Microsoft Exchange Server Best Practices Analyzer Tool scans servers running Exchange Server and identifies items that do not conform to Microsoft best practices.
* The Microsoft Exchange Server Performance Troubleshooting Analyzer Tool examines the performance of an Exchange Server messaging system, and identifies possible causes of performance problems.
* The Microsoft Exchange Server Disaster Recovery Analyzer Tool examines an Exchange Server deployment when an Exchange Server database fails to mount, and identifies possible causes of the problem.