Light weight, thin profile, low price and high battery life are the key driving factors, and though we don't yet know what the X420's price is going to be in the UK (it's $799 in the US) it's set to deliver on the three other factors.
As can be seen here, it uses the familiar tapered approach to design, raising up from just over a centimetre at the front to double that at the back, where the battery sits. MSI quoted a battery life of seven to eight hours and a weight of 1.6kg.

The compromise is inevitably performance, with an Intel dual-core 1.3GHz SU7300 CULV Core 2 Duo processor inside. We found the X420 responsive in use, but if you’re after a powerhouse then you should still be looking for a laptop with a faster, standard-voltage Intel Core 2 Duo.
With a sharp 14in screen at a standard 1,366 x 768 resolution, it's a cut above its sister laptop, the 13.3in MSI X-Slim X340 which we reviewed in June last year. What also makes it a little more interesting is the dual graphics – the sample at the show featured an ATI Radeon HD 5430, which you can use if you need the grunt, but for standard use you can drop back on the integrated Intel graphics.

There's also a curious dimpled trackpad. This isn't as irritating as it might sound, and it's helped by multitouch support: while this isn’t the revolution of multitouch on the iPhone, it's handy for zooming in on documents or web pages.
The keyboard is a fine if ordinary affair, with MSI following the current convention of isolated keys, but we were disappointed by the stiff mouse buttons. On a couple of occasions we really had to press down hard to make them obey our commands.

This may yet prove to be the Achilles’ heel of the MSI X-Slim X420, but we look forward to getting a finished product into the Expert Reviews Labs to see exactly how it performs: ergonomically, in 2D applications, and indeed in demanding games like Crysis.