Nikon D40 Help with low light shots?

Use a very fast lens, such as an 85mm f/1.8 lens, and get your sensor as sensitive to light as it's needs to ( Up the ISO ). There is not such thing as a miracle lens, some shots are just too dimly lit. Even an f/1.2 lens working with ISO 3,200 will not get some shots. Just use higher ISOs, and faster lenses.