Hometime: Windows and Doors

Tutorial covering styles and options, general installation instructions, and specialty installation instructions for Tilt-Pac windows, roof windows, and garage doors. Photographs, cautionary notes, and a windows and doors glossary.
http://www.hometime.com/projects/howto/windoor/pc2wd04.htm

Energy Efficient Windows

Benefits of energy-efficient windows, descriptions of how they work, and recommendations for their selection and use. Covers numerous glazing, frame, and operating types with detailed technical specifications and illustrations.
http://www.efficientwindows.org/

Handyman USA - Doors and Windows

Articles on squaring a frame, locks, sills, glazing, and sliding glass doors.
http://www.handymanusa.com/doors.html

Lowe's Home Improvement Warehouse

Illustrated tutorials on repair and replacement including garage doors and screens.
http://www.lowes.com/lkn?action=categorySelect&category=Doors%20and%20Windows

Missouri Extension Office

Instructions for replacing a broken window.
http://muextension.missouri.edu/xplor/hesguide/housing/gh5977.htm

MSN House and Home: Install a Patio Door

Step-by-step instructions for removing an old patio door, selecting a new one, and installing it. Includes materials and tools list and illustrations.
http://houseandhome.msn.com/improve/weekendprojects/patiodoor.aspx

The Old House Web

How to fix balky doors, out-of-plumb doors, pocket doors and weatherstripping.
http://www.oldhouseweb.com/stories/How-To/Doors/