Amazon Unbox

The big beast of internet shopping stepped into the movie downloading business when it set up Unbox in late 2006. It now boasts more than 5,000 movies for US users to rent or buy, though customers need to download its video-playing software. Rentals are mostly $3.99 and most purchases are priced at $14.99. Amazon has also teamed with Sony to launch a VoD service through Sony Bravia Internet Video Link.

Apple iTunes

Fresh from transforming the global music industry, Apple has moved into the movie-download business but has yet to shake it to its foundations in quite the same way, offering fewer than 1,000 titles to US consumers. The increasing memory of iPod hard-drives has opened the door to video downloads, and the films are designed to slide smoothly into Apple technology. For non-Appleheads, this may not be the easiest way forward yet, but things are changing. Sales only, between $9.99 and $14.99 per film.

CinemaNow

A pioneer in the business, having been set up in 1999, CinemaNow is widely regarded as the pick of the bunch in the US. As well as a library of around 5,000 titles, CinemaNow is the only download site that permits users to burn Hollywood films onto DVDs that can then be run on a DVD player (some of the others permit burning for back-up purposes). The site's five different ways of receiving movies - free, subscribe, rent, buy and burn - are popular with users. Rentals cost from $2.99, and sales between $3.99 and $19.95.

Movielink

Originally set up as a joint venture between Paramount, Sony, MGM, Universal and Warner Bros, Movielink had the inside track on relations with the US studios and was the first company to offer movies for legal download. Even though the studios decided last year to sell the operation to Blockbuster to allow themselves to distribute through other sites as well, Movielink still offers more than 4,000 films. Rentals start at $0.99 and sales from $1.99 to $19.99.

Vongo

More than 2,500 titles, a well-priced membership scheme and responsive customer service have turned Vongo into one of the fastest-rising players in the emerging US download world. Users can choose to pay per movie or join a membership scheme at $9.99 per month which allows them unlimited downloads. Unlike some other sites, however, browsing the Vongo catalogue requires the use of a credit card and the downloading of the site's software.