If you believe the headlines, the first rule about buying a laptop today is to forget about buying a laptop today. These bloated, annoying, space-hogging gadgets are apparently painfully obsolete compared to modern, sleek and sexy tablet computers.

But just hold on a minute! Laptops still outsell tablets four to one, and sales in 2012 are expected to top a quarter of a billion worldwide for the first time ever.

Laptops are faster and more powerful than tablets, have convenient full-size keyboards, are easy to connect to printers and cameras, and can glide between work and games in a flash. (Plus they can all actually run Flash.)

If you want an affordable, practical digital all-rounder, laptops come in an array of shapes, colours and prices that make flat, grey tablets look boringly identikit. There are laptops for students, laptops for artists, even laptops for mountain climbers. The only drawback to this variety is that it can be all too easy to end up with a computer that's either underpowered or overpriced for your needs.

First things first

You'll need two things when shopping for a laptop: a clear idea of what you want to do with it; and a firm budget. The good news is that all new laptops will be fine for checking email, surfing the Web wirelessly, working on office documents, and enjoying your photo and music collections. Where things start to get trickier is if you're heavily into gaming, want to watch (or edit) HD video or need a computer that works well away from power sockets or in extreme conditions.

Fix a budget before you start browsing -- although leave a little wriggle room for extras like a laptop sleeve, software, a separate mouse and possibly an external hard drive.

The basics

Laptops come in three categories. At the small and portable end are ultra-lights, designed for stressed-out executives formatting Excel spreadsheets on the Heathrow Express. Not to be confused with budget netbooks (we have a whole buying guide just for them), ultra-lights tend to be nicely designed, a little sluggish and shockingly expensive. Their screen sizes range from around 11.5 inches to 13 inches.

The next step up is everyday laptop computers, sometimes called notebooks, with screens from 13 inches to 15 inches. This is the sweet shop for laptops, where the most are sold and prices are keenest. Notebooks are light enough to carry occasionally and can usually manage half a day's work away from power, but budget ones often lack style, speed and build quality.

The final category is multimedia (or desktop replacement) laptops. These monsters have screens up to 17 inches (and sometimes even larger), and come packed with smart graphics cards, super-fast processors and lots of memory. They're the first choice of gamers, graphic designers and anyone who wants the power of an old-school desktop squeezed into a portable body. Well, we say portable, but these laptops can be heavier than a case of duty-free and bulky enough to need a Business Class seat to themselves.

Windows or Mac

Switch on the telly and it seems that everyone using a computer has an Apple Mac, except perhaps those hardcore hackers you see surrounded by monitors, empty pizza boxes and Star Wars figurines. In real life, however, the choice is not quite so clear-cut.

Macs are built well and age slowly but cost at least two to three times as much as the cheapest Windows machines. Even at those prices, the most affordable MacBooks have cramped screens and some performance limitations. Windows computers offer more choice and lower prices, but you'll need to stay on top of upgrades and security to get the best from them.

When shopping for a PC laptop, insist on Windows 7 software. It doesn't really matter which version, although anything running the Starter Edition is actually a netbook rather than a laptop -- hop over to our netbook buying guide for more info.

A bigger decision is what brand to buy. Unlike desktops, where even no-name companies can make great computers, the technical challenge of squeezing hundreds of components into a tiny case favours multinationals. Stick with top electronics brands (such as Sony, Samsung, Panasonic and Toshiba) or laptop specialists (Acer, Asus, HP/Compaq, Dell). Some retail chains also have 'in-house' brands that can be good value, if a bit plasticky.

Tech specs

Laptop specifications change all the time and consist of a brain-melting alphabet soup of letters and numbers. In general, there are three things to consider: the processor; memory (RAM); and storage. You can ask about other key components, like the graphics card and graphics memory, but don't expect to understand the answer -- check the model online if this is important to you.

Processors are virtually all dual-core these days, and are usually made by either Intel or AMD. There's little to choose between the two, although AMD silicon tends to be found in cheaper machines. Intel chips get more powerful as their model number increases (ie. an Intel Core i5 chip is faster than an Intel Core i3).

Processor speed, quoted in GHz, affects how fast it can crunch numbers. Anything above 2GHz is fine for everyday use, but gamers and video fiends should look for higher numbers, and especially for Intel's Turbo Boost feature.

RAM is the other thing that affects how fast your laptop runs. 2GB is an absolute minimum these days -- and step up to 4GB (or even 6GB) if you can possibly afford it.

Hard decisions

Hard drives generally range between 250GB (miserly) to 1,000GB (1TB, gargantuan). These determine how much data, including music and video, you can store on your laptop. Always buy a little more storage than you think you'll need, but don't bankrupt yourself. External drives are getting cheaper all the time, and space-saving cloud services are increasingly popular.

Apple's MacBook Airs, and some high-end Windows laptops, have fancy solid state drives that are faster, tougher and use less power. They're also achingly expensive and come in smaller capacities.

Screen and build quality

Always try to get your hands on a laptop before you buy. Start by looking at the screen indoors and -- if possible -- near a window or outside. You'll probably find that Apple and Sony screens have the brightest colours and best contrast. If you do have to buy from the specs alone, look for LED backlighting and Full HD for the best resolution, found on pricier machines.

'3D' is a buzzword right now and 3D laptops are already trickling out. While games and films can look stunning in 3D, the technology is still fairly young, fairly expensive and suffers from low levels of brightness and sharpness. Consume at your own risk.

Don't underestimate the importance of a good keyboard, trackpad or navigation nipple. Look for dedicated keys for mail, Web and especially media controls -- they all make smaller keyboards easier to use.

Open and shut the case a few times and hold it in both hands. How heavy is it? Does it flex or creak? How strong does it feel? While it's hard to beat Apple for solidity and design, all the big brands have premium metal-bodied models, and Panasonic even has fully waterproof and toughened Toughbooks.

In and out

The best laptops have a choice of connectors, including multiple full-speed USB ports, HDMI sockets for linking to media systems and memory card readers. Some laptops will have DVD or even Blu-ray players, although these add weight and suck power. A built-in webcam is great for Skype, Facebook or FaceTime video calls -- don't worry about its resolution.

Spare a thought for the battery powering all this techno wizardry. Manufacturers' battery life figures are a rough guide, but take them with a pinch of salt and don't expect to achieve day-long use without resorting to a socket. If you simply must have mobile freedom, choose a laptop with a replaceable battery and buy a spare immediately -- they can be hard to find a year or two down the road.

Ultrabooks

Finally, keep an eye out for 'ultrabooks', a new term coined by Intel to describe ultra-thin PC laptops rivalling the MacBook Air. Expect machined metal cases, solid state drives and even touchscreen displays to make the most of new finger-friendly Windows 8.

You can read our reviews of some of the first ultrabooks, including the Asus Zenbook UX21, the Toshiba Portege Z830and the Acer Aspire S3.