@ Babalaas- Grass Fed beef is much healthier than grain fed beef. A recent study by Cal State-Chico analyzed thirty years of research on grass fed versus grain fed beef. You can find a review of the research in a New York Times article from last year.
Grass fed cattle has less dietary cholesterol, less bad fats, more good fatty acids, and far more antioxidants than grain fed cattle. The increase in Omega-3 fatty acids are the biggest benefit next to the reduction in the cholesterol rich fats in the cattle. Research has proven that Omega-3 fatty acids promote cardiovascular health and reduce bad cholesterol. The increased CLA in grass-fed cattle has cancer-fighting properties, and reduces the risk of certain cancers like colon cancer. CLA has also been shown to support a healthy weight.
All that being said, it does not mean that grass-fed beef is as healthy as fish, but it is almost as healthy as skinless chicken breast. The key is moderation, but you should be able to enjoy grass fed beef more often than grain fed beef.