Controlling Memory Usage
With memory, more is almost always better. However, just adding more RAM to your server does not optimize performance. You must first determine whether you are making good use of the memory that the server has.
The biggest performance gains with IIS occur when you resolve issues related to insufficient memory. Before changing your hardware configuration, rule out memory problems. Monitor memory first to verify that your server has enough memory, and then move on to other parts of your server environment. Problems caused by memory shortages can often appear to be problems in other parts of the system.
Minimum Memory Requirements for IIS 6.0
To run IIS 6.0 with the Windows Server 2003 operating system, a dedicated Web server ...