The Insider: Hit the internet for your one-stop laptop shopping

The prices of new laptops have plummeted in recent years, with the very cheapest now being available for less than £300. Even the ones at the low-cost end of the spectrum tend to have fast processors and a decent amount of memory.

These days, it's portability and battery life that you tend to pay for. If you want a compact, lightweight laptop with a good-quality screen and a battery that lasts for at least three hours, you'll have to be prepared to pay upwards of £600. But if you're willing to make sacrifices on some of these features, the prices come down rapidly.

Sarah Kidner, the editor of Which? Computing, says: "Portability does come at a price, but it's possible to get a good-value, big-brand laptop for less than £800. Size and weight vary considerably, so consider what you need it for and whether weight, power, speed, features or price are important. It's worth future-proofing your laptop by choosing one with as much memory as you can afford. Some manufacturers will let you customise your laptop to get the spec you want – upgrading the RAM and the processor might help you to get a bit more life out of it."

When Which? recently tested 12 laptops, it picked out the Sony Vaio VGN-FW11E as the best model on the market. Among its highlights was the fact that it starts up in just 72 seconds – much quicker most computers – and that it is very easy to use. At 16.4 inches, its screen is slightly larger than the average laptop, which means that it's not a great option if you're after a lightweight computer. But its battery life of 146 minutes is higher than most of its peers. It's priced at £699.

If you're looking for something cheaper, Lenovo's ThinkPad R61e also scored quite well in Which?'s tests – and it costs just £350. It can keep going for almost three and a half hours, at 2.8kg, it's not too heavy, and its 2.1GHz Intel Core Duo processor is faster than some of its more expensive competitors.

Although all laptops fared relatively well in Which?'s tests, Sony's Vaio VGN-NR32M, priced at £429, came bottom of the list. It was penalised for its slow processing speed and lack of wireless connectivity. For the £429 it costs, you can find better elsewhere.

If it's just internet browsing you want a laptop for, it's worth considering a netbook, the cheapest of which are available for less than £200.

Where to buy

If you're looking for the cheapest computer you can get your hands on, now is a good time to be shopping around; many retailers are discounting laptops heavily. PC World, for example, has discounts of more than £200 on some HP laptops and is offering a handful of other models for less than £300. Laptopsdirect.co.uk is another great retailer worth visiting this month; its sale laptops start from as little as £240, and if you're willing to opt for a refurbished laptop you could pay as little as £130.

If you have a specific model in mind, it's worth using sites such as pricerunner.co.uk, whichcompare.co.uk or kelkoo.co.uk to see who's offering it for the smallest price. Which?'s best buy – the Sony Vaio VGN-FW11E – is offered by the likes of oyyy.co.uk for less than £600, while you can pick it up from Sony's own store, sonystyle.co.uk, for £629.

Five questions to ask

How big is the screen?

If you want to watch DVDs on your computer, you can get laptops with screens as big as 20in.

What's the battery life?

The worst barely make two hours, while the best will last well over three hours.

How fast is the processor?

Look for a processor speed of at least 2GHz if you're after a speedy machine. You'll get better speeds from a computer with a bigger memory.

Does it have built-in Wi-Fi?

Most new laptops have wireless connectivity already built in, but a few don't.

XP or Vista?

Microsoft's Windows Vista platform is meant to be faster and have better virus protection. Some cheaper laptops have only Windows XP installed.

The Insider is written in conjunction with the consumer group Which?. For more information on laptops, visit www.which.co.uk/laptops.

For information on staying safe online, buy a copy of 'Which? Complete Guide: Protect Your PC' at high-street retailers for £5.99. To get three issues of Which? magazine for £3, call 01992 822 800 and quote INADVICE.