Then do the following:

1. When the setup dialog appears for Microsoft Flight Simulator 2004, your going to find to installation types. The first one that you are going to land on is the custom install button. This option allows you to select where you would like the setup programme to install the simulator. If you want to install the simulator in a folder other than the normal Program files section, then use this option. The second option is the Express installation method. This options installs the simulator in the default Program Files folder area.
2. Select the installation option that you want and then press the spacebar on it.
3. If you are installing the 4-CD set, then you will be prompted to insert CDs 2, 3 and 4 as the installation progresses.
4. Once the Microsoft flight simulator is installed, press the Finish button.