The Apple iPad launched in the UK on Friday.

Even though its only been available in the US for just under two months, more than a million units have already been sold.

Sure, it's thin, sexy and - starting at £499 - relatively affordable, but it's less useful for business users who need to create and/or extensively edit professional documents such as reports, spreadsheets or presentations using a regular keyboard and familiar applications.

"The iPad has made a big splash," says Angela McIntyre, an analyst at Gartner.

"But it's not the only game in town. Convertible tablets make more sense for businesses wanting to take advantage of both the pen and keyboard."

Convertible tablets have two personalities. As with a traditional laptop, a convertible has a mechanical keyboard and hinged screen.

The difference lies in the convertible's special hinge, which sits in the center of the system's back and allows the touch screen to be rotated and folded down onto the keyboard to create a tablet.

Hardware buttons around the screen provide shortcuts or mimic the action of some of the more popular keys.

In other words, a convertible tablet provides both the best of both worlds: a powerful laptop that turns into a responsive touch-screen tablet.

There are trade-offs to choosing a convertible tablet over an iPad.

Convertibles are thicker, heavier and cost about three times as much as an iPad. But when you have to type a report or create a complex spreadsheet, there's no substitute for a mechanical keyboard.

In my experience, a screen-based virtual keyboard, which lacks the feedback of mechanical keys, just doesn't cut it.

Sure, you could carry around a separate Bluetooth keyboard to use with the iPad, but convertibles provide everything you need in one device.

And there are other features that distinguish convertible tablets from dedicated tablets such as the iPad.

To begin with, just about every convertible these days can be used with a finger or a pen, while the iPad responds only to finger action.

While it's cool to draw with your fingers, there's nothing like having a precise stylus when sketching a map or roughing out an electronic diagram.

In addition, most convertibles are equipped with webcams for videoconferences, and they can play Flash video and let you swap batteries without mailing the system back to the manufacturer.

Plus, the iPad's operating system is based on Apple's iPhone operating system, and that's a double-edged sword.

It provides access to an ever-widening library of apps, many of which are free - but the unit currently can't multitask and doesn't offer some of the business software that many companies require, such as Microsoft Office and Adobe Photoshop.

So, thinking of companies that need tablets that do more than the iPad, I looked at three of the newest convertible tablet PCs: the Fujitsu LifeBook T900, the HP EliteBook 2740p and the Toshiba Portege M780 - to see how they stack up against one another.

NEXT PAGE: Fujitsu LifeBook T900

  1. We put three to the test
  2. Fujitsu LifeBook T900
  3. More on the Fujitsu LifeBook T900
  4. The HP EliteBook 2740p
  5. More on the HP EliteBook 2740p
  6. Toshiba Portege M780
  7. More on the Toshiba Portege M780
  8. Conclusions