Labs

Light laptops

At the bottom of each review, there are five star ratings: one for Performance, another for Battery life, a third for Features & Design, one for Value for Money and a final Overall rating. We don't just pluck these figures out of the air: they're calculated using a complex mixture of benchmark results, objective scores and subjective quality ratings.

Performance

The Performance rating is based on each laptop's scores in our 2D and 3D benchmarks. Each score in the overall 2D performance graph is relative to a 3.2GHz Pentium D 840 desktop PC with 1GB of PC2-4300 RAM. If a laptop scores 1.10, that means it's 10% faster than the reference machine overall.

The figure is derived from the system's performance in a number of real-world applications, including Microsoft Word, Excel and Access, as well as Photoshop. We also run media-creation benchmarks, and converting an AVI file to MPEG2 and DivX, including converting a WAV file to WMA, MP3 and Ogg Vorbis formats.

We use Far Cry and Call of Duty 2 to test each laptops 3D performance. Far Cry is set to Very High detail at 1,280 x 1,024 with HDR, then at 1,600 x 1,200 with HDR and 8x anisotropic filtering. Call of Duty 2 is run at the same resolutions with High textures then Extra textures respectively. The driver is set to 4x anti-aliasing and 8x anisotropic filtering.

Battery life

We run three tests to measure battery life. In our light-use test, we run a simple timer application with the brightness set to medium until the battery runs out; in the intensive test, we push the processor to its limit with our multitasking benchmark and maximum brightness. This combination of tests gives us a maximum and minimum battery life. In both cases, we use Vista or XP's power-management settings most appropriate for longevity and performance respectively. Finally, we also measure the time each machine takes to recharge to 95% from empty, while switched on and idle. This may not sound vital, but it can make a difference for those travelling workers who need to recharge their notebooks every night.

Features and Design

The Features & Design score is calculated using a huge array of scores that we give to each machine, based on objective measurements such as the range of ports and connectivity, expansion and hard disk capacity. We also give scores to any bundled software and the type of warranty given.

This rating also includes some subjective scores, which are decided by a panel of judges; this helps to overcome any bias resulting from one person's taste. The subjective scores cover all those items that can't be measured objectively, such as the quality of the screen and design of the chassis.

Value for Money

The Value for Money rating is based on a weighted average of the Performance, Battery life and Features & Design scores. We then factor in exactly how much each PC costs (including delivery) to give a bang-per-buck result.

Overall

The Overall rating is a straight average of the Performance, Battery life, Features & Design, and Value for Money scores.