Instructions
During Gameplay
Open the game file and begin playing.
Press "alt" and "tab" at the same time. These immediately minimize the program and move to the desktop screen.
Press "alt" and "tab" again to restore the game to full screen.
Windowed Mode
Right-click on the "Sims 2" icon on the desktop and select "Properties."
Locate the field labeled "Target" and put the cursor at the end of the text entered in the field (it should end with ".exe").
Add "-w" at the end of the text within the "Target" field.
Click on "Apply" and "OK" the change. Open the game using the shortcut icon and it will immediately begin in Windowed mode, which can be minimized by clicking on the minimize button (the symbol looks like an underscore: _ ) at the top of the window.