Check with Lenovo sales. However, I would not hesitate to get it with windows 8. While I use and plan to stay with windows 7. I have been running windows 8 in a virtual machine on the Y580 windows 7 machine. While I am not messing around with an upgrade, if you get windows 8, get one of the following utilities to return the start menu. --classic shell, free, http://www.classicshell.net/ I tried this and it works great. --Start8, 30 day free trial, then only $5, http://www.stardock.com/products/start8/ Both Classic shell and Start8 have received good reviews with Start8 getting the best reviews. As mention, I tried classic shell in my virtual windows 8 machine, have not tried start8
You can always pay for Windows 7 and it should work fine. All the drivers are seemingly available for both operating systems. Since it doesn't use touchscreen, you won't be missing out on any fancy Metro gestures.
Don't pay extra for Win 7, Windows 8 is fine, especially if you run Windows Classic Shell. It give you back your start button, and all your slide out tile for program files, and what ever, including a slide out tab for the Metro window apps in case you want to use them, Plus its Free! I'm in no way affiliated with the app, but it reall helped several newer users who were lost. I'm an experienced user, but I use it myself.