When it comes to veggies, dont worry about "organic" or "non-organic." A lot of these veggies were genetically engineered for flavor as well as size. There as some exceptions to the rule, but as long as you wash 'em, veggies of all types are okay.
Its the meat you gotta worry about. You want to find growth hormone free, antibiotic free, properly fed meat. It'll cost you extra, but the flavor is much noticably better, and the meat itself is much more clean.
Did you know that most chicken sold in stores has to be injected with dye so it has a "natural" color? Its because the chickens are so sick their entire lives, the meat comes out grey. Blech. Gross.