Video-game enthusiasts are looking forward to the release of Microsoft's motion-sensitive video-game control system, code-named "Project Natal," later this year. Maybe investors should be doing the same.

That's the underlying message in an analysis of Project Natal issued this morning by Sarah Friar and Derek Bingham of Goldman Sachs. The analysts make a series of assumptions -- including an $85 retail price for the camera-based system -- and estimate that Natal will boost Microsoft's revenue by $1.7 billion in its 2011 fiscal year (which begins in July 2010) and $2.3 billion in its 2012 fiscal year.

It's a bullish position, to say the least, and it will no doubt be greeted with some skepticism. For a bit of context, Microsoft's entire Online Services Business posted only $3 billion in revenue in the 2009 fiscal year, out of $58.4 billion in companywide revenue.

The Goldman Sachs analysts obviously believe consumer demand for the motion-sensitive Project Natal device will be big. In a note to clients, they say they expect Natal to reach a 56 percent "attach rate" less than two years after its launch, meaning that more than half of new and existing Xbox 360 owners will buy Natal for their consoles. By comparison, they say, Nintendo's Wii Fit achieved a 41 percent attach rate over a similar time period.

"Xbox has been predominantly targeted towards a more hardcore gaming demographic, which is different from the family oriented approach of Wii and Wii Fit," they write, adding that "Natal now adds a hook for the more casual gamer."

Cumulative sales of the Xbox 360 were 39 million worldwide at the end of 2009. Project that out to 2011 and 2012, take into account the analysts' estimates of attach rates for Natal, multiply the result by their $85 price assumption, and you can see how they start getting into the realm of billions of dollars in revenue. On Microsoft's bottom line, the analysts predict that Natal will translate directly into increases in earnings-per-share of 4 cents (2 percent) in fiscal year 2011 and 7 cents (3 percent) in fiscal year 2012.

"Internally, Microsoft views Natal’s introduction as significantly extending the lifecycle of Xbox 360 to 10 years (until 2015), which is double the average for consoles," they write. "If this is the case this could have significantly positive ramifications for the longer-term margins of [Microsoft's Entertainment & Devices] group."

Microsoft itself hasn't talked in detail about the financial potential of Natal, which is expected to be released under a different name. However, the question is likely to be asked by analysts on the company's post-earnings conference call Thursday afternoon, now that Microsoft has confirmed a fall release.

Natal will use its camera-based system to let a user control the action on screen by moving around, without the need to hold a controller. It's part of the company's shift toward "natural user interfaces." Nintendo's Wii popularized the idea of motion controls with its Wiimote and companion nunchuck. Sony last week delayed, until fall, the release of its new PlayStation 3 motion controller.