The three-day event officially kicks off Wednesday. But the big announcements start on Monday, with a news conference by Sony about its forthcoming PlayStation 3 (PS3).

This will be followed by Nintendo and Microsoft on Tuesday.

All to play for

Sony currently dominates the console market, having sold more than 100 million PlayStation 2s, compared to 24 million Microsoft Xbox consoles and 21 million Nintendo GameCubes.

With the debut of the PS3 due in November, Sony has to prove it has a world-beating successor on its hands.

The new system boasts cutting-edge computing, graphical and audio capabilities, including a high-definition Blu-ray DVD player.

But it has yet to show off playable games, as well as demonstrating its online gaming network.

Sony needs to persuade gamers that it is worth waiting for the console to come out in November, despite an expected high price tag, and not snapping up an Xbox 360 instead.

Microsoft says it has sold more than three million consoles worldwide since its debut in November.

The software giant is expected to outline new games for its console, in a drive to keep up the momentum.

Games line-up

One of the most anticipated titles is Halo 3, according to game website IGN.

The original Halo game has sold millions and helped to boost sales of the first Xbox.

In a posting in its website, Halo developers Bungie has tantalised fans by hinting at a big announcement in the coming days.

Other big-hitting titles for the Xbox 360 expected at E3 are Gears of War, Saint's Row Splinter Cell: Double Agent and Viva Pinata.

One of the other games that many are looking forward to is the latest Zelda title.

Nintendo offered a first glimpse of The Legend of Zelda: Twilight Princess at last year's E3 so fans will be waiting to see if it lives up to the hype.

The Japanese games giant could surprise at E3 with its Wii console, which analysts say it could be a surprisingly strong contender.

The machine cannot compete with the cutting-edge computing prowess of its rivals. Instead Nintendo has focused on making a console that is fun and easy to play.

Its approach is reflected in the console's controller, a wand-like remote control that players wave in the air to play a game.

The console is also expected to be less costly that its rivals, which could help in winning over parents.

Cash crisis

More than 400 companies from 90 countries are expected to show off their wares in an attempt to grab a slice of an industry worth an annual $25bn globally.

They will be seeking to create a buzz around forthcoming products at a time when the games industry is suffering from falling sales and higher costs.

Last week, games giant Electronic Arts revealed a loss of $16m for the last quarter of year, while top publisher Activision also announced a loss of $9.2m over the same period.

This is due to the switch to a new wave of consoles. Gamers have been saving their cash to spend on the new systems, with few interested in buying games for consoles that are on their way out.

In addition game makers face higher investment costs as they grapple with the new technologies in the new consoles.

Alfred.Hermida-INTERNET@bbc.co.uk