Nintendo confirmed on Wednesday that the Nintendo DS has shipped 100 million units worldwide as of March 6, over four years after the handheld's official launch.

Originally unveiled at E3 2004, the DS' clam-shell, dual-screen design and lack of graphical horsepower elicited scoffs from many onlookers at first, particularly when compared to the sleek Sony PSP, which emerged a year earlier. With unproven technology and a new handheld competitor backed by the PlayStation brand, it was uncertain whether or not Nintendo could replicate the success of the Game Boy Advance.

But Nintendo was able to surpass combined worldwide sales of all the different versions of the Game Boy Advance hardware, which had sold over 81 million units as of last year, thanks to a smart DS hardware strategy and first-party Nintendo games that showed third-party developers how to create games for a touch-enabled system.

Following the original DS' launch in late 2004, Nintendo in 2006 introduced the DS Lite, which led many original DS owners to become repeat hardware buyers. Consumers were drawn to the incremental updates: a brighter screen, a slimmer profile and an iPod-inspired aesthetic.

Now Western consumers await the arrival of the Nintendo DSi, the latest update to the hardware, which adds two cameras, larger screens, a memory slot and a slimmer profile made possible in part by the the removal of the GBA cartridge port. Already launched in Japan in order to re-ignite flagging sales, it is tempting gamers to buy a DS for the third time. The DSi is due in the U.S. and Europe in April ($170, £150).

In an October interview following the unveiling of the DSi, Nintendo of America president Reggie Fils-Aime told Venture Beat, "Nintendo has a legacy of constantly updating the system. If you look at handhelds, we had the original Game Boy, the Game Boy Color, the Game Boy Micro, the Game Boy SP and the DS. That’s a way to keep consumers happy and to drive ongoing creativity. It’s also a great way to increase competitive pressure."

The DSi will also bring Nintendo closer to the company's lofty goal: to average one DS hardware unit per person. It's more of a symbolic target, but with the handheld having hit this latest 100 million landmark, Nintendo understandably has high expectations.

The family room-based Wii is poised to mirror the success of the DS, as they share clear similarities. They both debuted to initial confusion (and at times mockery), were pitted against rivals that boasted superior graphical prowess , were created with accessibility and the mass market in mind, they have unique interfaces that are capable of offering a new gameplay experience, and were created with the intention of disrupting the games market. In the U.S. and Europe, the duo routinely tops sales charts.

A first-party software stable backed by Mario, Zelda, Metroid, Pokemon and Donkey Kong doesn't hurt either. In the past fiscal year, Nintendo reported 15 first-party DS games that sold over 1 million units, including Nintendogs, New Super Mario Bros., Brain Age, Pokemon Diamond and Pearl and Mario Kart DS. The firm says 83 DS titles in total have broken the million mark; seven have topped 10 million.

The GBA was out for just three-and-a-half years before the DS hit the scene. But with the DS, it seems that Nintendo is perfecting the practice of drawing out the life of a machine while still making it commercially appealing. In other words, it's hard to tell when exactly the DS will go into a happy retirement to make way for Nintendo's next chance to prove handheld market leadership.