Mini CADViewer is a compactfree CAD viewer.It is designed to be easy to use, even for those with no prior CAD experience. It allows you to move and zoom in/out drawingview at will. It supports DWG, DXF formats.
SimplePDF is a free and open-source PDF viewer. With its only 2 MB it installs and loads within seconds. It displays PDF and multiple other eBook formats. The program comes in many languages and is very easy to install.