Is a 40 inch LCD TV too small for a large bedroom?

That would depend on your lifestyle and family size. It is possible to fit a 40 inch TV into a room of this size. The question you will need to ask yourself before finalizing your decision is whether or not you need a lot of space in this room to move around comfortably. Also, it would be a good idea to consider whether or not you would watch TV enough to make it worth your while.