Vegetarian and Vegan vitamins?

Are there any special vitamins I need to take if I'm considering becoming vegetarian, and maybe vegan? I have PCOS and I'm supposed to cut out all gluten, dairy, and processed foods. So to me, it seems like it'd be easier to become vegetarian or vegan, since I'm not supposed to have dairy and I'm not supposed to have eggs. Do you have a particular recipe you like that's vegetarian or vegan? Know any good recipe books I could get?