Concept cars... you've seen them grace the catwalks of Geneva, Milan and Detroit, all subtle curves and power, never to be seen on any road. Until, that is, some high-powered executive decides "Well, why not? Let's build it." And the next thing you know your neighbours have bought one.

The XPS M2010 is Dell's concept car; it's a million miles away from what you'd expect from the computer giant. It's also eye-wateringly expensive.

Trying to describe the M2010, or even trying to explain what it offers, is a challenge. Yes, it's a desktop. But then again, it's also a desktop replacement notebook. You can even carry it around, although at over 8.4kg you're going to have to be a keen follower of the Californian Governor's diet and fitness regime to take it anywhere.

When you first set eyes on it, it looks for all the world like a largish executive case, even down to the large Dell logo embossed on the carrying handle. But releasing the two catches holding the lid down reveals all. The lid holds a 20-inch display - yes, that's right; a 20-inch TFT screen - and a fully adjustable 1,680 by 1,050 pixel widescreen at that. With the screen open, the M2010 gets a 'wow' of amazement from the vast majority of people who see it.

The centre section of the base is dominated by the optical drive, which is a slot unit that is built in such away that the whole section pops open for you to load the disk, accompanied by a nice whirring noise. Even the controls for the drive are something different; a row of touch-sensitive icons which are back-bit by blue LEDs that only light up as you move your finger along the controls. Then they fade slowly away - a very neat effect.

Another surprise comes in the form of the detachable keyboard which is Bluetooth-enabled, meaning you can sit the unit on a table and relax in your favourite chair to use it. Some people may not like the fact that the keyboard uses a trackpad and not a ball control for the mouse, but you soon get used to it and the keys are good and responsive.

But its not all style over substance. The M2010 is powered by an Intel Core Duo T2600 CPU clocked at 2.16GHz and backed by 2GB of PC5300 667MHz DDR2 memory, all of which gives it a very respectable Sysmark04SE score of 240.

Its also perfectly at home playing games. When tested with 3DMark05 at a resolution of 1,024 x 768 pixels, it gave a score of 6,040 and a FarCry frame rate of 80fps. That's more than enough to keep the average gamer happy, thanks to the 256MB ATI Mobility Radeon X1800 that Dell has installed in it. Even the audio sounds better than most laptops; four speakers sit under the lower half of the screen and there is a sub-woofer built into the underside of the chassis.

For storage Dell provides two 100GB hard drives configured in a RAID 0 (Striped) array which, although giving fast performance, doesn't offer much in the way of data protection. But if that is your concern, there is an option for two 120GB drives in a RAID 1 (Mirrored) array (add £94 plus VAT). To offload data or backup files you can use the aforementioned optical drive, which is an 8-speed, dual format, dual layer DVD burner.

You also get Dell's Premium XPS Service warranty included in the price, which lasts for 3 years and includes on-site and gaming support.

This is something totally left-field from Dell, and it's a conversation-stopper. Don't think of it as a desktop or laptop, more as a very capable portable or space-saving PC (perhaps it's the first in a new generation of 'luggable' computers?). One thing's for sure, not many of the neighbours will own one of these.