Mac users have the ability to view RAW images natively in OS X. However, Windows users can have the same ability by installing the Microsoft Camera Codec Pack (http://www.microsoft.com/en-us/download/details.aspx?id=26829)
For more details on viewing and editing RAW images natively in Windows see this article:
http://www.techradar.com/us/news/photography-video-capture/cameras/how-to-view-and-edit-raw-natively-in-windows-984141
