If you're looking for the next must-want Windows laptop, Lenovo might just have the answer. It announced a new, slimmer version of the X1 Carbon at CES in Las Vegas on Sunday night and we've already had a play with the new laptop.The New Lenovo ThinkPad X1 Carbon is the lightest 14-inch Ultrabook on the market and is thinner than the previous model after Lenovo managed to reduce much\u00a0of the bulk used to make the display touchscreen. If you're happy to ditch touch it's thinner still, coming in at 17.7mm thick.Combine that with a 1.31Kg weight and you end up with a very portable laptop indeed. But that's just the start of the technical prowess of the Lenovo ThinkPad X1 Carbon (2014).There are two display options available for touch users including a 14-inch HD+ 1600 x 900 resolution TN touchscreen display and a 2560x1440 IPS display with 10-point multi-touch display.Beyond the display, which is stunning by the way, you get up to 8GB of on-board RAM, up to 512GB SSD for storage and Intel's Haswell-powered Intel Core i7 processor powering it all.Windows 8.1 comes as standard as does a backlit keyboard, a 720p HD Camera for Skype calling, and a fingerprint scanner as is almost standard for Lenovo.More connectivity options for on-the-go use, including 4G LTE, Bluetooth 4.0 and near field communication (NFC).All that power will drain the battery in around 9 hours according to Lenovo, but it can be recharged to 80 per cent in just 50 minutes. That's going to be more than ample for coffee shop workers or hovering around a plug at an airport before a long flight.While all that sounds standard progression stuff, what is new, different and improved for 2014 is an adaptive Keyboard technology that\u00a0allows controls to appear dynamically when needed, simplifying the user interface.That adaptive keyboard technology is really just a strip filled with capacitive buttons etched in electroluminescent ink. That's different from E Ink as the buttons glow rather than stay static, but they are mono, not colour and are pre-set to specific icons rather than being able to be turned into anything.Replacing the F keys along the top of the keyboard, the display changes depending on the app you are running. Turn on Skype for example and the keys change to be more focused on what you need, including quick access to the mic or video controls. Dragon offers a different set too, as does Office. There are around 45 different icons available for developers to take advantage of.When not in that app you can press a button and turn the keys into something else, with the idea that more apps will support the feature in the future.The keys are actually a single touch-sensitive strip but very responsive. We don't want to see the entire keyboard like this, however. That is standard Lenovo stuff, but very good.In terms of performance we didn't really get to push the laptop that hard in our brief play, but the time we did spend with the laptop didn't suggest it would be anything other than what you would expect of a machine with these specs.\u00a0Lenovo has made a a very good thin laptop here and one that will certain challenge Apple and it's MacBook Air range. If you're a Windows user, based on our hands-on time with the device, this is one to take a closer look at. From what we've seen, we are very impressed.