I've been using this Longbow Previewer application, I like it because it fully integrates with the preview pane in Windows Explorer and also in Outlook too. For me it's particularily good because it also checks my DWG digital signatures and tells me the DWG version also - here's the link http://www.longbowsoftware.com/Previewer.php
Anyway, hope this is useful to someone
Thanks for the tip Tom. I decided to give it a try after reading you post - I didn't realize it also does an Audit and a Purge check on the DWG file too! Very pleased with it.
Others, you should check it out on Autodesk Exchange http://apps.exchange.autodesk.com/ARCH/en/Detail/H