Take the time to understand the goals of the project (What will the organization gain by doing the upgrade?) as well as the scope of the project (What is included and what is excluded from the project?).
Understand all the applications that connect with Windows Server 2003 and whether they are critical, near-critical, or simply nice to have.
Document the research process for each application, because this will prove to be very valuable if problems are encountered during the testing process.
Create a lab environment that is as close to the final end-state of the upgrade as possible. This reduces the variables that can cause problems at the least opportune time.
Test applications for compatibility with both typical endusers of the application and application administrators who support, maintain, and manage the application.
