Steve,
Came loaded with Win7 Pro and a OEM dvd with 8.1. In the process of adding the SSD and trying to clone the factory (Win 7) drive, I totally screwed up the original (OS)drive and decided the easiest course was to do a fresh install of 8.1 on the SSD. Hint, make sure you create a 'repair' (system backup) disk before you start this type of operation (I knew that - just lazy). All the drivers for my (3) audio/midi interfaces (Alesis I/O 26 is my primary) worked just fine although they only specified up to Win 7. After all the hoopla here about band-in-a-box, I purchased a copy of BIAB 2015 (audiophile ver.). It's an amazing little program (well actually not so little) and a great instructional tool for someone wanting to learn different genre's, especially jazz.

chas