A few of the houses my techs go to try this route. Doesn't work out as well as you'd think most times. DSL and other options can't really handle the load and the ones that can are overly expensive. So generally if your planning for something like this your still going to be dealing with your cable provider if you want truly fast hsi at a reasonable price.

The way most cable plans are setup right now the extra cost for the higher speed broadband is often enough to cover the cost of video service so your not really gaining much if you go with the higher speeds and dump video, generally you'll be paying more for the your hsi since it's no longer a bundled option as well. Should consider maybe buying your own dvr, your own modem/router and just get exp basic and rent a cable card decoder, save a bunch of cash that way.