V for Vegetarian

I wanted to see if becoming vegetarian could be one of the most important and effective actions I can take to ease the strain on the Earth's limited resources, protect the planet from pollution, prevent global warming, and save countless species from extinction... 

I am not a vegetarian though I did attempt to be one for a while in my 20’s, but I am pondering this quote:

‘if everyone skipped one meal of chicken per week and substituted vegetarian foods instead, the carbon dioxide savings would be the same as taking more than a half-million cars off our roads. ‘  [from Become an Eco-vegetarian]

edamame - a vegetarian staple

But then there is the fact that it is argued that the average rich world vegetarian may not consume much less of the planet's resources than the average moderate omnivore: a report for the Worldwide Fund for Nature (download pdf) on the impact of food production pointed out that highly processed vegetarian meat substitutes or foods made of imported soya might actually use more arable land and resources than their beef or dairy equivalents. Deforestation in the developing world to grow cheap soya for human and animal feed is a major issue in climate change. 

However some would say that the way we breed animals for food is a threat to the planet, that it pollutes our environment while consuming huge amounts of water, grain, petroleum, pesticides and drugs.

So are vegetarians more eco than meat eaters?