HOUSTON, Nov. 10 — Last month, a local landscaping firm prompted a furor here by telling a gay couple in an e-mail message, “We choose not to work for homosexuals.†The message quickly made its way around the Internet, and the company, Garden Guy Inc., was bombarded with threats and hate mail. But since then, the company’s owners say they have gained far more business than they have lost. In an interview Friday, Sabrina Farber, 34, co-owner of the company with her husband, Todd, 37, said the company had picked up $40,000 in new business in the past two weeks,...