BENTONVILLE, Arkansas: The world's biggest retailer, Wal-Mart Stores, is to offer its US customers an intriguing twist on movie downloading.

Consumers can buy a DVD copy of Superman Returns which will contain instructions - for an extra cost - on how to download the same movie to "portable media players, PCs and laptops".

Wal-Mart is offering a solution to the problem that consumers cannot legally buy a DVD, make an electronic copy, and then transfer it to portable digital video devices.

This initial launch is expected to open the way for a DVD-less download service from the retailer, although details and timings are sketchy.

Data sourced from Wall Street Journal Online; additional content by WARC staff