Another option if you want to use Integrated Mode:
If you use ASP.NET 2.0 you should be covered because ASP.NET ignores the system.webServer section due to this entry in machine.config:
<section name="system.webServer" type="System.Configuration.IgnoreSection, System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
If you use ASP.NET 1.1 you can put the same entry in its machine.config file and ASP.NET 1.1 will simply ignore IIS <system.webServer> entries in your web.config files. This allows you to work in Integrated Mode on IIS7 and continue to work as usual on XP and W2K3.