Duane, as I'm sure you know, the cost-per-foot of 12/3 or 14/3 is about twice that of 12/2 or 14/2, respectively, so cost is not a significant factor. I would consider eletrical noise reason enough to separate the lighting and equipment circuits, so I'd recommend using two separate runs.

There are noise filters available that the audio/video and/or computer gear plug into that keep the generated noise away from the house wiring to reduce signal swamping. X-10 signals are timed to be transmitted at the zero-crossing point of the sine wave, and require a relatively quiet power line.

Larry
www.fineelectricco.com