Vendors are lining up behind ultra-mobile PCs as the next big thing, devices that will make computing all-pervasive by letting users take their Windows PC anywhere.

Bill Gates made similar claims for Microsoft’s Tablet PC concept when he unveiled it in 2001. Despite this, Tablet devices have struggled to break out of the vertical application niche, even though the software necessary to support stylus input has now become a part of standard editions of Windows.

UMPCs have come up against many of the same criticisms levelled at Tablet PCs: that the battery life is not good enough; there is no clear “killer app” for them; and that laptops are actually a better match for user requirements.

However, there are signs that UMPCs might avoid the Tablet PC’s fate. OQO’s Model e2 seems to be a hit with both travelling executives and IT staff, perhaps because it really does offer the facilities of a full PC in a pocket-sized format. If more UMPC designs can emulate its success, there could be wider adoption in future.