Plans and specifications are provided in either PDF or tif format. Some sets are in a zipped format which requires extraction after download.
To view pdf’s you may need the latest version of Adobe Reader: http://www.adobe.com/products/acrobat/readstep2.html
To view tif’s you may need one of the many tif viewing products such as On-Screen Takeoff Plan Viewer (download application for free):
http://www.oncenter.com/products/plan_viewer.asp
http://www.winzip.com/downwzeval.htm?wzdm