Netflix came up with a brilliantly simple concept when it launched its service in 1999: rent DVDs by mail for a flat monthly fee. You choose the movies you want on the Netflix Web site, receive from one to eight discs at a time (depending on the pricing plan you've chosen), and--using a prepaid envelope--return them in the mail whenever you're finished viewing. The set monthly billing rate means that the decades-old bane of the video store--late fees--is a thing of the past. In fact, not only has Netflix's pricing strategy prompted brick-and-mortar rival Blockbuster to adopt a "no late fees" strategy at its retail stores, the old-line video rental giant has chosen to fight Netflix as well, offering a very similar online rental service starting in August 2004 that's since been enhanced by limited integration with its brick-and-mortar video stores. With retailing superpower Wal-Mart already having pulled out and Amazon opting for digital delivery with its Unbox service, here's how the two main players in the online DVD rental market stack up against one another.