It all started in 2005 with an ambitious promise by Massachusetts Institute of Technology professor Nicholas Negroponte. He claimed that within two years his newly formed One Laptop Per Child (OLPC) project would produce a $100 (£50) laptop capable of handling web access, word processing, email and more.

It was a pledge that intrigued technology enthusiasts and bargain hunters alike. If it were technically possible to mass-produce a machine that could handle all the basics of computing for just £50, why were most people forking out hundreds of pounds? For a second PC or a travel companion, we would have been quite happy to sacrifice the powerful processor and large screen in favour of extreme portability and an exceptionally low price.

It was all immaterial, of course, because OLPC's XO laptop wasn’t designed with us in mind. Negroponte’s aim was to help bridge the digital divide by encouraging governments in emerging economies to buy millions of these devices and hand them out to schoolchildren for free.

Then last summer saw the unveiling of the Asus Eee PC 701. Asus’ first ‘mini-laptop’ ran a Linux operating system instead of Windows, weighed just 1kg and made a traditional ultraportable look cumbersome by comparison. And crucially, it cost just over £200. It captured the hearts and minds of all who saw it.

In the 12 months since Asus first demonstrated the Eee PC, it’s been a runaway success. The company expects to sell five million machines worldwide this year. Unsurprisingly, other laptop makers are queuing up to get in on the act.

At the Computex IT show in June, mini laptops were the big story. Intel claimed as many as 25 manufacturers were planning to build models based on the Atom processor, its chip for portable PCs. Dell, Acer and HP are just three of the big names to have joined Asus in the fast-growing mini-laptop market.

Sure, the Eee PC and its competitors are less powerful than other laptops. Windows is available only on the most expensive options, the keyboards on some models are so small they can be a hindrance to the touch-typist, and a 10in screen is as much as you can expect from the display.

But these products are perfect for a number of applications. You might use one as a second PC or for browsing the web from the sofa, for instance. Some come into their own when you’re on the move; others are designed specifically for children.

We've looked at several mini laptops in this month's cover feature and, while not even OLPC has managed to hit that magic £50 price point, some suppliers – notably Elonex with its £99 One laptop – aren’t far off.

Build your own PC

But perhaps the best way to save a few pounds when buying a new PC is to get your hands dirty. Elsewhere in this month's issue we have a step-by-step guide to building your own desktop. We’ve looked at the various components you need to build a computer from scratch and found that, with a bit of digging around, you could put together a system for £164, and in just two hours. Alternatively, you could use our advice to create a dream PC built from premium components that’s capable of getting the most from the latest games and high-end applications.

So whether you’re on the look-out for an ultraportable mini laptop, an ultra-low-cost desktop or an ultimate PC, read the August issue of PC Advisor - on sale now.