Windows 8.1 on T400

First impressions - everything feels snappier and more stable. The dual homescreen - regular desktop and Metro-based UI needs getting used to. Instead of installing software, you now download apps from the Windows Store. And apps auto-update. You can still install software the old way if you want to. To access the Windows Store, you'll need an online account though.

There are apps for music, video, food, travel, health, news, photos, games, finance, etc. They work quite well and easy to use. No options or config for the power users to tweak. As long as I can keep using the desktop, I'm happy.