Redmond (WA) - Over five million people have tapped into Nintendo's DS Wi-Fi service, 18 months after it debuted.

The DS, which has been the top selling handheld system every month since it launched in November 2004, has more than 60 games that use the online service.

The DS has a more robust Wi-Fi compatible library than its main rival, the PSP, but users still complain about restrictions that prevent voice chat and require mutual system registration before some games can be taken online.

The overall market for online gaming is also increasing, with all five main gaming systems sporting built-in Internet capabilities.  The Xbox 360's online service reached five million users in just a couple months after the system was released.