Labs

Big-brand notebooks

At the end of each review, there are five star ratings: one for a notebook's Performance, another for Battery Life, a third for Features & Design, then 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 array of benchmark results, objective scores and subjective quality ratings.

Performance

We put each machine through its paces in a rigorous series of tests with real-world applications such as Word, Access and Photoshop using the same tests for PCs and notebooks.

The overall 2D result is relative to a score of 1.00 from our reference PC - a dual-core 3.2GHz Pentium D 840 system with 1GB of PC3200 RAM, a 10,000rpm Western Digital Raptor hard disk and an Nvidia GeForce 6600 GT graphics card. If a machine scores 1.50, it's 50% faster than our reference machine overall.

Given the wide price range of notebooks this month, we make use of all the levels of our Call of Duty 2 gaming test. The lowest price models - as well as some dearer but unsuitable models such as the Sony VGN-TZ21WN/B - failed to run any of the tests and shouldn't be considered if 3D gaming is a priority. But, as the graphs on the right show, many of this month's laptops are perfectly capable gaming devices, even at high resolutions.

We use one or more of three quality settings to suit each notebook's graphical capability. At "low" settings we use a resolution of 1,024 x 768, ensure anti-aliasing and anisotropic filtering are turned off in the driver, and set the textures setting to Normal.

We also run those with capable graphics cards at our considerably more intensive "medium" 1,280 x 1,024 settings. This also involves switching on 4x anti-aliasing and 8x anisotropic filtering, and raising the textures to High for a tougher test. Finally, those that cope with this are tested at our "high" settings: 1,600 x 1,200 with the punishing Extra textures enabled - a setting that taxes even those graphics chips with 512MB of onboard RAM.

Battery Life

We run three tests to measure battery life. In our light-use test, we run a simple timer application with the brightness around 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 gives us a minimum and maximum 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 & Design

The Features & Design score takes into account an array of objective measurements, such as the range of interfaces, hard disk capacity and the capabilities of the optical drive. We also factor in software bundles, but, more importantly, points are given for the amount and type of warranty, as well as each company's performance in last year's Reliability & Service Awards. Any features related to performance, such as the graphics card, CPU and memory, are left to the Performance score.

The rating also includes some subjective points, which are decided by a panel of judges to help 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 build quality, style and the quality of speakers and any accessories.

We line up all our laptops together, with the same desktop background and brightness setting. Then each judge runs the same test audio and video files to judge the screen and speakers, and independently rates the keyboard, style and build quality. The results are then averaged to give the ergonomics scores you see in the feature table, and then factored into the Features & Design score.

Value for Money

The Value for Money score is based on a weighted average of the Performance, Battery Life and Features & Design scores; we then factor in exactly how much each machine costs (including delivery) for 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. Occasionally, it may appear higher or lower than expected due to rounding.