Toshiba was initially amongst the five companies that launched the Tablet PC format alongside Microsoft back in 2002. It has continued its support with a range of clamshell devices.

The Toshiba Portégé R400 (£1878 inc. VAT) is the latest incarnation and is being billed by Toshiba as 'the symbol of sophistication' and it's easy to see why. With its crisp white and black lines, the design is definitely more sophisticated than the average machine. That said, it feels less like a business tool and more like a consumer machine.

Digitised screen

Being a clamshell, you'll find it looks more like a laptop, but the 12.1-inch screen sits on a pivot, so you can twist the panel back and write directly on to the digitised screen with the supplied electronic pen.

This is the first such panel we've seen using LED backlighting instead of standard fluorescent tubes and the difference is amazing, as the brightness and image quality is far sharper, with no hint of the haze usually associated with similar digitised displays.

With an overall weight of 1.8kg, this machine is light enough to carry around for large portions of the day and with a battery life, under test, of 290 minutes, you won't be tied to a powerbrick.

We were surprised to find how quickly this machine ran. Windows Vista Ultimate loads and runs swiftly and is by far the easiest version of Tablet PC software we've used.

Perhaps the most appealing aspect of this machine is that is comes with true mobility built in, in the form of a Novatel Wireless 3G/HSDPA adapter.

The software that accompanies it is easy to use and manage and allows you to send and receive emails on the move, as well as allow your IT manager to update your system on the fly. Toshiba bundles a range of tools, including HDD docking technology, to make the most of the R400.

All this requires a powerful specification to maintain the performance and while Toshiba has opted for a low voltage processor in the form of the Intel 1.2GHz Core Duo U2500, we found it handled tasks with great ease. This was helped in part by the addition of 2048MB of memory.

Tablet PCs have been accused in the past of not delivering on the usability side, but we found the Toshiba Portégé R400 a pleasure to use. The screen is a good size and highly responsive and Toshiba has installed a host of applications that make setting up and managing the device a good deal easier.

True, you'll have to pay a premium for this level of quality, but if you're serious about having one of the most impressive Tablet PCs around, then you'll find it money well spent.