If you managed to build this just during the Christmas break, I'm really impressed! Looking good!

Unfortunately I cannot give you advice on your lighting question - I used a fluorescent under cabinet light for marquee lighting. It is cheap, and it does a good job. A smart power strip makes the light, the monitor and the amplifier turn on or off when the PC changes its power state. Also, speaking of marquee, take some light source and a marquee sized sheet of paper, and check whether those two upper wooden supports cast a shadow in the top marquee corners. If you plan to have your marquee corners black, most likely this will not be an issue. Otherwise, use a chisel and a hammer to chip those support corners.
Do you plan to install T-molding?