The 2011 MacBook Air refresh retains the form factor introduced with 2010's line of ultraportables, but makes significant improvements to the core technologies. Apple has switched the ageing Core 2 Duo chips for new Sandy Bridge processors, the Mini DisplayPort has been replaced by a versatile and powerful Thunderbolt port and the backlit keyboard makes a welcome return too.

The new MacBook Air range (check out our 13-inch MacBook Air review) contains four off-the-shelf versions. The cheapest offers an 11-inch screen, 64GB of flash storage and 2GB of memory for £849. The next in line, also an 11-inch model, has a 128GB SSD and 4GB of RAM for £999. A similarly spec'd 13-inch MacBook Air costs £100 more, while for £1349 you can get a 256GB flash drive.

You can check out a video review of the MacBook Air below:

All four MacBook Airs have dual-core Intel Core i5 processors (1.6GHz for the 11-inch models, 1.7GHz for the 13-inch notebooks), with Intel HD Graphics 3000 integrated graphics. Each has two USB 2.0 ports, usefully positioned with one on each side of the notebook, and a Thunderbolt port. The 13-inch model also has an SD card reader. All the Airs also have a FaceTime camera that supports full native resolution on the built-in display and up to 2560 x 1600 pixels on an external display.

The MacBook Air we're reviewing here is the more expensive of the two 11-inch models, but enhanced by the optional customisations available when ordering at the Apple online store. The processor has been beefed up to a dual-core 1.8GHz Intel Core i7 and the flash storage drive has been doubled in size to 256GB. Naturally, these enhancements take their toll on the price.

This custom-built MacBook Air costs £1,399, which is more expensive than the priciest off-the-shelf model. But is it worth the extra money, and do you really need all that power in an 11-inch MacBook Air?