technicaly, its less strenuous for a pc to never be turned off than to turn it on a nd off.
This is mainly attributed to the simple fact that when computer components are in use, they heat up, thus expanding, and when they are turned off, the cool, contracting. Thus putting more stress on the components.
Also a very interesting fact is that if a light bulb is never turned off it will never burn out. Theres a reason why a lightbulb never simply dies. Itll always die when you turn it on.
And in response, if only the top is accesable, how do you intend to put cd's into the cd drive?