The OQO Model 2 is a UMPC designed by OQO inc. It is one of the smallest PCs in the world, and as of 2007 is the smallest computer that runs Windows Vista. Bill Gates demonstrated a pre-production OQO Model 02 in his keynote address at CES 2007 to promote the launch of Windows Vista.

Direct competitors include other models of the Microsoft Ultra-mobile PC line, such as the Samsung Q1, or third-party concepts like the Sony VAIO UX series of handheld computers, or Vulcan FlipStart. Note that the Handheld PC line previously marketed by Microsoft run Windows CE, which is visually similar but binary-incompatible.