Lenovo recommends Windows.

* Lenovo has measured against other 14" notebooks that comply with the Intel Ultrabook® specification. Lenovo ThinkPad X1 Carbon - 2.99lbs, Dell XPS 14Z - 4.12lbs, HP Envy 14 Spectre - 3.95lbs, Samsung Series 5 14" - 3.94lbs, Satellite U840 - 3.81lbs, Lenovo Thinkpad T430u - 4.05lbs, Fujitsu Lifebook U772 - 3.15lbs.