Hey..... guess what empleh? You solved my mystery! Big time thanks.
OK, this extra comment is for anyone who is confused like I was regarding saving files within the Hardware Render Buffer feature.
When I rendered withinin the "Render/Render Frame" menu, I needed to save the file manually. That is, I needed to go to "File/Save Image" option from the menu within the render window.
When saving in the Hardware Render Buffer window, the file saving feature is a bit different as empleh mentioned above. File saving is automatic when you "Render Sequence". What I didn't do, was to set the file extension in the "Image Output Files" section within the "Attribute Editor". When I speak of extension, I do not mean "Image Format". I mean the subsection labeled "Extension". Make sure you set this to: name.ext.
I found a little tutorial that may help anyone with wireframe rendering. A little task oriented, but may produce results you are looking for. The URL is: http://www.geocities.com/jozvex/tutorials/wireframe.html
Good luck.
holibeck@adelphia.net