Physician-investors who think thatinsider buying by corporate executives isa harbinger of a positive move for thecompany's stock haven't had much tosmile about lately. Stock sales by companyinsiders are way ahead of buys, whichare at their lowest level in severalyears. If you want to find out when theinsider-selling spree turns into a buyingjag, a couple of Internet sites can help.Vickers Stock Research (www.vickersstock.com), for instance, lets you seewhich insiders are trading and whetherthey are buyers or sellers. Being aninsider doesn't give you a clear crystalballâ€”some have a better track record atcalling the direction of their company'sstock than others. Thomson Financial(www.thomsonfn.com) keeps track andassigns a score to each insider, based onwhether the stock went down after theysold or up after they bought.