If you are contemplating to move over (upgrade) to IIS 7.0 from your existing Web hosting on either IIS 5.0 or 6.0 this is a very useful Technical White Paper link. It talks about various aspects of improvements in IIS 7.0 dealing with Management, Performance, Extensibility, Security and Deployment.
Migrating a Large, High-Volume Web Site to Internet Information Services 7.0
Cheers!