The following games are scheduled to be broadcast in High Definition. There will also be a Sunday night game vs. STL that will be shown on ESPN-HD. This is only for Time Warner Cable in Houston, I don't have any information about other providers (DirecTV, Dish Network, etc.).
Astros HD Telecasts
Wed. May 10, 9:00 p.m. at Los Angeles Dodgers
Fri. May 26, 6:00 p.m. at Pittsburgh
Sat. May 27, 6:00 p.m. at Pittsburgh
Mon. May 29, 3:00 p.m. at St. Louis
Tue. May 30, 7:00 p.m. at St. Louis
Mon. June 26, 6:00 p.m. at Detroit
Tue. June 27, 6:00 p.m. at Detroit
Fri. Aug 4, 8:30 p.m. at Arizona
Sat. Aug. 5, 8:30 p.m. at Arizona
Fri. Aug 18, 7:00 p.m. at Milwaukee
Sat. Aug 19, 6:00 p.m. at Milwaukee
Thu. Aug. 24, 6:00 p.m. at Pittsburgh
Fri. Aug. 25, 6:00 p.m. at Pittsburgh
Fri. Sept. 8, 7:00 p.m. at Milwaukee
Mon. Sept. 11, 7:00 p.m. at St. Louis
Tue., Sept. 12, 7:00 p.m. at St. Louis
Wed. Sept. 13, 1:00 p.m. at St. Louis
TWC (in Houston) plans to broadcast these games on ch-299 (IN-HD2)