If you are a network administrator, you will need this tool to help you assess all the pc in your network whether they are capable to be upgraded to windows vista.
from Microsoft website:
The Windows Vista Hardware Assessment is a tool that will find computers on a network and perform a detailed inventory of the computers using Windows Management Instrumentation (WMI). Through use of the detailed inventory data, the tool will assess and report whether the computers can run Windows Vista, where to find drivers for devices on the computers, and provide recommendations for hardware upgrades, where appropriate.
The Windows Vista Hardware Assessment tool does not require the deployment of agent software on the computers being inventoried and assessed. It provides a secure, quick, and easy way to determine which computers, in a networked environment, are Windows Vista ready.