By Melissa S. Monroe, San Antonio Express-News Knight Ridder/Tribune Business News
Feb. 27--In the Rio Grande Valley, San Antonio grocery giant H-E-B has quietly rolled out its newest weapon in a fight to stave off customer defections to the nation's biggest retailer -- Wal-Mart.
The weapon is H-E-B Plus, a grocery that's coming to San Antonio next year but much sooner -- in just weeks -- to Waco, Austin and Houston.
The first H-E-B Plus is more than 20 percent bigger than the average H-E-B, with one-third of its space devoted to general merc