WSS3.0\MOSS2007 and "Integrated managed pipeline mode" of IIS7

Problem Description:
SharePoint site is on WIN2k8\IIS7\WSS3.0-SP2 and you have created a sample web app (blank site) which is running well with IIS7 "Classic managed pipeline mode" but when you change it to "Integrated managed pipeline mode", It does not work and throws an error message "500 internal server Error".
Discussion ,Action taken and Results:
As discussed, MOSS 2007 use “Classic application pool mode” in IIS 7 for the SharePoint site since MOSS 2007 use IIS 6.0/ISAPI functionality through an ISAPI module and that is part of “Classic application pool mode” .
If we will use the “ Integrated Request Pipeline” for the SharePoint 2007 site you will not be able to browse to the site.
Following is the TechNet article which talk about that SharePoint use “Classic application pool mode” for the Application pool.
1: http://msdn.microsoft.com/en-us/library/bb909693.aspx (How to: Verify or Correct the IIS Configuration for an Application Pool)
Details are:
1. On the Application Pools page, review all application pools for Team Foundation.
• Under .NET Framework Version, verify that v2.0 appears.
• Under Managed Pipeline Mode, verify that Classic appears.
2: http://technet.microsoft.com/en-us/library/cc262485.aspx (Determine hardware and software requirements (Office SharePoint Server))
Details are:
Windows components
After you have installed the operating system and applied all critical updates, you must configure the computer to be a Web server by enabling Internet Information Services (IIS) 6.0, including:
• Common files
• WWW
• Simple Mail Transfer Protocol (SMTP)
You must configure the server to use IIS 6.0 worker process isolation mode. This is the default setting in new installations. However, if you have upgraded from IIS 5.0 on Windows Server 2000, Run WWW in IIS 5.0 isolation mode is enabled, and you must change this setting to use IIS 6.0 worker process isolation mode.
To enable e-mail notifications, you need to configure incoming and outgoing e-mail settings. To configure sending e-mail alerts and notifications, you must specify an SMTP e-mail server. To configure your installation so that your SharePoint sites can accept and archive incoming e-mail, you must install the IIS SMTP service

Additional info:
Integrated Request Pipeline:
Think of the integrated request pipeline as the essential set of linear steps that must occur every time a page is served up (as seen in Figure 2). Typically, some sort of authentication must take place, followed by authorization to retrieve content, determination and execution of the handler needed for that content, performance of any necessary logging, and finally sending a response. The integrated request pipeline provides IIS 7.0 the flexibility to run different application frameworks at the same time. For example, you can run Forms authentication on top of PHP content with a custom logging module, all together in the same pipeline.

Each Web site on the server has an integrated request pipeline and can be run in one of two modes, Integrated and Classic. Integrated, the default, allows particular pieces of functionality to be plugged into the pipeline, giving you granular control over the request process. For compatibility, Classic mode reproduces IIS 6.0/ISAPI functionality through an ISAPI module into the pipeline. This is very helpful when migrating your applications to IIS 7.0.
More info : http://technet.microsoft.com/en-us/magazine/2008.03.iis7.aspx
Classic application pool mode:
When an application pool is in Classic mode, IIS 7 handles requests as in IIS 6.0 worker process isolation mode. ASP.NET requests first go through native processing steps in IIS and are then routed to Aspnet_isapi.dll for processing of managed code in the managed runtime. Finally, the request is routed back through IIS to send the response.
This separation of the IIS and ASP.NET request-processing models results in duplication of some processing steps, such as authentication and authorization. Additionally, managed code features, such as forms authentication, are only available to ASP.NET applications or applications for which you have script mapped all requests to be handled by aspnet_isapi.dll.