It's no secret that Microsoft has developed Windows 8 primarily for tablets with touchscreens. Yet, for all the repeated assurances that the new operating system will scale to work on any device with any screen size, there's little evidence that it will.

The main problem centres around the fact that the new Metro user interface, which is geared for fingertip control, is mated to the old Windows desktop, which isn't. It's a bit like having both Mac OS X and iOS rolled into one.

Of course, Microsoft's argument is that Metro isn't limited to a small screen; it works just as well on a 27in widescreen display as on a 10in tablet. That's true but the real issue is that most people - and we're talking billions here - use programs such as Word, Excel, PowerPoint and Photoshop.

Not a single one of these has a Metro version yet, and it's no surprise: touchscreens are excellent for consuming content, but not much good for creating it. Few people would choose to use an onscreen keyboard over a physical one for typing an essay, but most people would rather use their fingers than a mouse to swipe through thumbnails of photos or music to find the image or track they're after.

Another problem with Windows 8 for the desktop is that vertical touchscreens don't really work. Indeed, Steve Jobs went on record in late 2010 on the subject, "We've done tons of user testing on this, and it turns out it doesn't work. Touch surfaces don't want to be vertical…after a short period of time, you start to fatigue and after an extended period of time, your arm wants to fall off. It doesn't work; it's ergonomically terrible."

Laptops are particularly tricky as their screens are hinged and move backwards if prodded. That's the last thing you want in a touchscreen. It needs to be rock-solid. The same goes for touchscreen PC monitors: they shouldn't wobble if touched, and should ideally tilt backwards to provide a more comfortable angle. Try propping your keyboard vertically on the desk and you'll immediately see the problem.

Windows has had the same basic interface for almost 20 years. We're not against change if it improves things, and we're not afraid to embrace new ways of working. The phenomenal growth of tablet sales is testament to this, but to attempt to force this way of working on PCs may be short-sighted, not least because virtually none have a touchscreen.

Yes, it's possible to use Windows 8 with a keyboard and mouse but it takes more effort and more clicks than it does in Windows 7. It takes four clicks just to shut down or restart, and that's just one example.

We're sure Microsoft will take consumer feedback seriously and iron out many of the flaws in the Consumer Preview, but PC manufacturers will also need to sit up and listen. They need to produce touchscreens that tilt much further back than existing designs and remain planted when poked. Finally, software developers need to release Metro versions of their applications so that the old desktop becomes a thing of the past. Until this happens, Steve Jobs' verdict on touchscreen PCs will remain true.

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