Windows Server 2008 R2 includes changes to the kernel and user-mode API’s to support virtualization, scalability, performance, power-management, and networking enhancements.  As a result, your existing application may require modifications or design changes, particularly if the application includes kernel drivers.

Microsoft provides free test tools and other resources to help you.   Benefits include participation in logo programs and global application marketing exposure.

See the application readiness portal for more detailed information.