As mobile computing has grown in popularity, laptops have become broadly grouped into two camps: desktop replacements and ultraportables.

While the former are big, bulky machines that specialise simply in power and performance, the latter group presently constitutes one of the more interesting frontiers of mobile computing.

The growing maturity of feature-rich smartphones and ultra-mobile PCs (UMPCs), combined with an increasing demand for an always-on mobile lifestyle, has made the ultraportable market a particularly fertile one at present. And PC makers have been quick to take advantage.
1. How small is too small?

As we've already mentioned, there are some smartphones that are on the verge of being miniature laptops themselves, and the laptop market has downsized to meet them head on.

As a result, while in the past ultraportables were simply standard laptops with smaller screens and lightweight components, now the lines are increasingly being blurred by micro PCs like the Asus Eee. With a 7-inch screen, sub-1kg weight and £220 price tag, it takes ultraportable computing into entirely new ground, and expect other devices to follow in months to come.
2. Touchy, feely

If possible, try out a laptop before committing to buying it. Unlike a desktop PC, you can't change the keyboard or screen down the line, so make sure the keyboard is comfortable to type on and the display to your taste.

If you plan on watching DVDs or video files, opt for a Super-TFT screen, which has a glossy coating and is more suitable for movies. The downside is the coating makes the screen more reflective. Of course, some ultraportables dispense with an optical drive altogether to save space, so watching DVDs won't even be an option.
3. What's inside?

If you're familiar with a typical desktop PC's credentials, glancing at an ultraportable's specification may be depressing reading. But remember that components are often chosen specifically for their size and low power usage, and this comes at the cost of raw power.

As a result, you'll commonly find ultraportables powered by a 1.2GHz processor, which is outdone by even the slowest of desktop processors. But this is the price you pay for portability.

Remember that an ultraportable is defined by size and weight, but prices, features and purpose vary widely beyond that starting point. As with buying any laptop, decide on a budget, look at what features are essential to meeting your specific needs and approach the market with a clear picture of what you want.
4. Mobile considerations

There are some specific considerations to bear in mind when buying a laptop for use mainly on the move. Battery life is particularly important, and poor battery life should really be a deal-breaker if you're not prepared to carry around a bulky extended life battery.

Build quality is also important. The smaller the laptop, the greater the chance of lightweight materials having been used in its construction. But that doesn't excuse flimsiness or poor build quality, especially if it's to be carried around regularly.
5. Recommendations

If you're in the market for an ultraportable, clearly mobility is a primary concern. Quite how far you want to take this portability will determine just what your money will buy.

Typically, Ultra Low Voltage processors and compact construction don't just mean a sacrifice in performance for portability, but also increased cost. This doesn't mean that that performance and portability are mutually exclusive, but expect to pay more for uncompromised computing power in a highly mobile package.
6. Buyer's checklist

* Processor type and speed
* Hard drive capacity
* Memory
* Operating system
* Display size
* Optical drive
* Weight