Greeetings,
Here are our minimum requirements. Apache is not required and EE will run on IIS. I believe you’re referring to the Requirements page in our User Guide which it mentions a setting for Apache; but that is intended as a note for those running EE on Apache.
We do find that EE tends to run better on *nix hosting. Permissions are more easily handled, and using Apache means you have access to mod_rewrite; which as far as I am aware, is not available on IIS - instead you’d need to use ISAPI if you needed similar functionality.
Please post back if you have any other questions.