Is it possible for Noteworthy Composer to play back through a midi keyboard? If so how?
First, you need to connect your keyboard to your sound card.
Then, in NWC, click Options in the Tools menu. There go to the Midi tab and select Midi Out, MPU-401 (or whichever name your sound card driver uses for the output) as the playback device.
This should enable your keyboard as a playback device.
Note that you may additionally need to enable certain settings in your keyboard in order to make the playback work best. You may need to set receiving channels, or perhaps enable an External mode. See your keyboard's manual for more information.
Jussi's advice is correct. However, there are some computers (especially laptops) that do not have the capability to connect the sound card to a MIDI keyboard. For such machines, you would need to add hardware that allows the connection.