They also observe that Microsoft's emphasis on a single core for all variants on an operating system makes even 2001's Windows XP less practical on some platforms. On notebooks such as the Eee PC or Classmate PC, XP consumes twice as much storage as custom Linux installations, which ASUS, Intel, and others often use to pare down the size of the OS without sacrificing the features they need.

Microsoft's focus on a singular code foundation has also prevented it from porting its operating system to cellphones and handhelds. Unlike Apple, the company is currently incapable of translating its OS directly to a mobile version. Windows Mobile is instead based on Windows CE, a separate though related platform originally meant for PDAs, while the iPhone and iPod touch use a variant on Mac OS X which shares the same core but prunes features unnecessary in portables.

Intel has also said that most devices in the Mobile Internet Device class, such as the Lenovo IdeaPad U8, will need Linux or other alternative software both to run smoothly and to provide enough free capacity on a given drive.

MacDonald and Silver instead suggest that Microsoft develop Windows 7 or later versions as a modular operating system. The Redmond firm could then add only the code necessary for a given device. It would also eliminate chronic problems associated with Windows by letting Microsoft fence off applications that don't need access to certain aspects of the operating system.

Microsoft hasn't discussed most details of Windows 7 but says it will represent a larger change than Windows Vista when it appears in 2010.