Driver Signing for Windows Server 2003
Microsoft uses digital signatures for device drivers to let users know that drivers are compatible with Microsoft Windows XP, Windows Server 2003, Windows 2000, and Windows Me. A driver's digital signature indicates that the driver was tested with Windows for compatibility and has not been altered since testing.
Microsoft requires digital signatures for all devices provided in systems that carry the "Designed for Windows" logo. For Windows XP, certain limited application files (kernel-mode file-system filter drivers used by anti-virus software) can also receive digital signatures.
Windows uses the presence or absence of a driver's digital signature to evaluate the quality of the drivers it attempts to install. Windows XP, Windows Server 2003, and Windows 2000 will warn users if they attempt to install drivers that don't have signatures. System administrators and individual computer owners can also choose to set operating-system policies that will prevent the installation of drivers that do not have digital signatures.
Microsoft encourages the use of digital signatures for drivers to advance system stability, to provide a better user experience, and to reduce total cost of ownership for customers.
For more information, see Driver Signing.