A new poll suggests that one in five Americans plan to buy a tablet computer within the next three years. That's great news for Apple, RIM, HP Palm, and the hardware companies like Motorola who are building Android-based tablets.

It's horrible news for Microsoft, which stands poised to miss the tablet surge just like it missed the first three years of the consumer smartphone explosion.

Every tablet purchase is a Windows PC not purchased. Microsoft has no specialized tablet OS. There's no dedicated product team working on one--responding to tablets is simply part of the Windows group's mission.

Microsoft's Windows Phone 7 platform might do very well on a tablet, much like Apple's iOS moved from the iPhone to the iPad, but Microsoft isn't even considering that strategy right now. Instead, the company is betting on Windows 7--its PC desktop operating system--with perhaps a few new user interface elements layered on top. That's what it showed at the 2010 Consumer Electronics Show, and that's what it's showing next month at the 2011 CES as well.

The next version of Windows, currently codenamed Windows 8 (or perhaps Wind8ws), may indeed have a special version tailored for tablets. But it won't be out until 2012 at the earliest. That's more than two years after the iPad's debut, and long enough for other tablets to establish a huge head start--just like Apple with the iPhone and Google with Android phones.

Worst of all for Microsoft, nearly 40% of survey respondents plan to use their tablets for business. That has dire implications for Microsoft's core enterprise business--each tablet potentially replaces corporate purchases of laptops running Windows, and requires IT departments to support non-Windows clients to connect to corporate applications. Once that happens--as it has with the iPhone--IT departments might begin to question why they're running so much Microsoft back-end software like Exchange for email, giving competitors like Google a wedge into Microsoft's most important business.

The poll of 2,288 Americans was conducted by Harris Interactive over three days in November. It was sponsored by Fuze Box, which creates Web conferencing and other real-time communications products.