Here's an excerpt from Wikipedia on the differences between brown and white rice:
"Brown rice and white rice have similar amounts of calories, carbohydrates, fat and protein. The difference between the two lies in processing and nutritional content. If the outermost layer of a grain of rice (the husk) is removed, the result is brown rice. If the husk and the bran layer underneath are removed, the result is white rice. Several vitamins and dietary minerals are lost in this removal and the subsequent polishing process. A part of these missing nutrients, such as B1, B3, and iron are sometimes added back into the white rice making it "enriched", as food suppliers in the US are required to do by the Food and Drug Administration (FDA). One mineral that is not added back into white rice is magnesium; one cup of cooked long grain brown rice contains 84 mg of magnesium while one cup of white rice contains 19 mg.
When the bran layer is removed to make white rice, the oil in the bran is also removed. A recent study has shown that rice bran oil may help lower LDL cholesterol.
Among other key sources of nutrition lost are fatty acids and fiber.
Brown and white rice also differ in their chemical makeup. White rice is a simple carbohydrate which the body processes almost directly into sugar. Brown rice however, is a complex carbohydrate that the body can use very effectively."
Plus brown rice simply tastes better! Save white rice for sushi and risotto.