The Texans are mostly on CBS if not every game. Last year CBS did not broadcast many games in HD so the Texans were not in HD much. This should change this year. CBS reportedly will off 5-6 games a week this year in HD and all games will be in HD in 2008.
Here is a link to the next 2 weeks of HD sports - http://www.hdsportsguide.com/
Chiefs and Texans are in HD.