Organic meat may be good in small doses. However most of the meat today is not the same as it was centuries ago. The book "The China Study" does a good job at explaining the diseases caused by meat.
http://rawfoodsos.com/2010/07/16/the-china-study-my-response...
http://www.proteinpower.com/drmike/cancer/the-china-study-vs...
They're both very well written and put some serious doubt into the validity of Campbell's conclusions.
Things such as Vitamin C decay away in the meat with the current slaughter to serving times, and the corn diet instead of the proper grass diet lead the beef to be made up of Omega 6 instead of Omega 3 fats.
Meat itself may not be perfect, but modern factory meat is horrible. Corn Fed, Trough Locked Cows are horrible for you.
BUT, the China Study book is very questionable. There's a very thorough rebuttal here:
http://www.amazon.com/review/R2JXW2AQARAXZL/ref=cm_cr_rdp_pe...
It's a very good rebuttal. I agree with a low-ish meat diet, but the China Study book (as opposed to the actual study) is riddled with errors and bad science.
"The China Study: Fact or Fallacy?" http://news.ycombinator.com/item?id=1499447
Edit: I'm not a vegetarian by the way.
As one of the links explains, the data shows almost the opposite. More meat was weakly protective.
That's completely crazy. Meat and fat are the easiest things to digest. There is no such thing as an allergy to meat, whereas something like a quarter of people have various allergies to grains, or various nightshade related plants.
Pretty much all plants have various toxins to prevent digestion. That's why plants in general need so much heavy processing and cooking to eat safely. You can eat a freshly killed animal raw reasonably safely. Eating a lot of raw grains or sweet potatoes could kill you.