That looks like just what you need. A Mini DVI to HDMI adapter. Even if it says its ready for audio, you still need the other audio cable as the MacBook won't support audio out through the Mini DVI.
That looks like just what you need. A Mini DVI to HDMI adapter. Even if it says its ready for audio, you still need the other audio cable as the MacBook won't support audio out through the Mini DVI.