Sam Gentile on IIS 6.0 on Microsoft Windows Server 2003
Sam wrote about New Request Processing Architecture of IIS 6.0 on Win2K3. IIS now consists of two kind of processes, Kernel-mode and user-mode (and then there are Worker processes). Read about the new architecure and more in Sam's article. Truly a next generation stuff in terms of Reliability and Scalability. Good read.
There is also an article on Microsoft Windows Server website which provides a very good technical overview of IIS 6.0