I get organic or locally grown fruit and vegetables when I can, but that's unfortunately impossible living in Canada, since it's impossible to grow fruit and vegetables half the year. Avoiding meat is instantly good for the environment, though.
They probably don't take into account the manufacturing costs of building a car, either. I don't actually own a car, so I'm sure that saves some pollution.
Additionally, do you really eat more when you walk to the store? Personally, I eat the same amount no matter what I do. If I walk to the store, I burn some energy, and if I don't, it gets turned into fat or whatever. That's probably the main reason that that article has issues -- people don't generally eat more when they exercise.
<edit> incidentally, the article talks more about refrigeration emissions than anything, which means if you avoid frozen meals and other crap like that, you're helping. Avoid beef and frozen meals, and you're set.
<edit2> This quote is awesome:
“The way he is running around telling people they should shoot cows,” Lawrence Hunt, head of Silverjet, another budget airline, told the Commons Environmental Audit Committee. “I do not think you can really have debates with somebody with that mentality.”
That's totally an ad hominem attack, totally meaningless. And it seems to imply that supports of meat eating don't want cows to be killed? Guys.. cows are killed every day, but he doesn't say you support "running around telling people they should kill cows."