I was having the same problem and I didn't want to download any additional software to do this.
If you go to file explorer and click on 'View' (upper left corner) and then 'Preview Pane' then any time you click on a file or document it will preview it on the right of the window.
Hope this helps.
I'm thinking of switching to Windows 8 from OS X on my 2009 MacBook Pro. Its the small things in OS X that brought me to Mac in the first place but now it is getting old. Windows 8 looks fresh so I'm thinking of switching to it. One of these small things thats really useful in OS X is quicklook.
When you are in Finder (like Windows Explorer) if you press the space bar any file that you have highlighted gets previewed. This is much quicker than opening whatever app handles that file and it also gives you some basic useful information about the file like size, type, etc.
If I would just like to see what an mp3 is quickly but dont want to import it into iTunes I can just press the space bar and be done with it in seconds instead of opening iTunes, importing it, creating clutter (if I dont want the file in iTunes at all). Likewise instead of opening a photo app I can just quickly look and browse through pictures.
Does Windows 8 have a similar feature that works fast and is useful?