Many people are abhorred by some of the modern and inhumane methods by which animals are farmed and the conditions that they're subject to. It is honourable to wish to reduce the suffering of animals. It is good to insist that animals are farmed in ethical and compassionate ways. However, I think it is far better to support humane animal farming by buying meat produced by humane methods, rather than avoiding meat altogether. The massive meat industry is not affected by such passive vegetarian non-consumption protests. But if market forces dictate that ethical production methods sell better, the meat industry does listen. If you are morally concerned about the welfare of animals, as you should be, it is better to buy meat farmed ethically than it is to shun meat altogether, because that makes the entire market swing towards ethical methods and has a bigger impact than resorting to (self-harming) vegetarian protest.
The Economist magazine's special report (2006) explained that buying meat from those conforming to ethical standards is more effective at changing the industry than simply abstaining from meat altogether - "consumption, rather than non-consumption" is "far more likely to produce results" according to Ian Bretman of Fairtrade Labelling Organisation (FLO) International, the Fairtrade umbrella group.