Actually, there was a Penn and Teller Bullshit episode about this very topic. They reported that in blind taste tests, you couldn't tell the difference or even preferred the non-organic, regular grocery stuff. The production costs of growing organic food are also higher and have less yield, AND the foods have a higher risk of going bad.
Finally, I've always found the term "Organic Food" to be kind of stupid. Aside from chips with olestra, all food is organic.