indeed it is if you are using IE. Simply set IE to use our PDF-XChange Editor plugin as the default .
In the Editor's preferences go to File Associations --> View PDF files in Internet Explorer --> Yes
You can try setting the mime type with the following reg keys, but it is a moving target, Microsoft seem determined to stop file and mime associations being programatically set. We do have customers who use the Editor in SAP environments so I am sure it can be done.
Windows Registry Editor Version 5.00
I hope that helps. I'm keen to hear how that goes.