Network cabling tips and tricks , need help?

I have Comcast cable in my house and thought about somehow attaching ethernet cat5 cable using the exisiting Coaxial runs to somehow make network drops to the different rooms in my house. Thoughts that come to mind is using compressed air and pushing a string tied to a washer that is looped around the coaxial and then pulling on the string to pull the cat5 cable along. What are your thoughts. Perhaps something electronic and motorized to pull the washer along? Ultimately, all the cables lead into my garage and I'll just set up my patch panel, router and broadband modem there.