Move the entertainment center to a corner of the room where it does not block any natural light. Placing the entertainment center in the corner will help open up the room, rather making you feel like the entertainment center is this massive article you need to shuffle around.
Place comfortable sofas and chairs with high legs opposite the entertainment center. Picking high-legged pieces of furniture will make the room seem roomier. Avoid sofas and chairs that are lower to the ground, as they will make the space feel cramped.
Paint the walls a light color. A light color will give the room a spacious and airy feel, while a dark color will make it seem smaller. Light colors like lemon yellow, mint green and periwinkle blue complement the shades of wood that most entertainment centers consist of.
Hang light, gauzy cafe curtains from the windows. This will prevent you from blocking the natural light of the room, which will make the room seem airier rather than cramped.
Remove any wall-to-wall carpeting, and expose or install wood floors. This will make the room feel bigger, as wall to wall carpeting can make a room feel smaller. If you truly love carpet, add a few light-colored throw rugs.