In early June, Apple released what is arguably its most significant upgrade to Safari yet: Safari 4. In typical Apple fashion, the company was quick to deem it the “world’s fastest and most innovative browser.” Today, we’re setting out to find if that bold claim is indeed true, and we’ll be breaking down the features of it–along with its fiercest competitors–on both the Mac and PC side.One of the nicer things about Safari 4 is that Apple has made it available for both Windows (XP and Vista) as well as its