Gottheil didn't mention it, but Apple may have another kind of opportunity to grab additional sales share. In 2006-2009, when Microsoft stumbled with Windows Vista, Mac share almost doubled, according to measurement firm Net Applications. That was the heyday of the "Get a Mac" advertising campaign, featuring actor Justin Long and humorist John Hodgman, who portrayed a Mac and Windows PC, respectively, and poked fun at Vista and its quirks..