Posted By:
MWPete,
Just double left click on the file (.pdf format) and it should open right up with Adobe Acrobat Reader. If you've already downloaded Lew's invoice, you can also right click on the filename and choose "open with..." (again, use Adobe Acrobat).
If you don't already have Adobe Acrobat, I believe it can be downloaded for free here -- http://www.adobe.com/products/acrobat/readstep2.html