This will shake your OOPS fundamentals ( Somewhat :) )

This is a four article series written by me way back..

http://www.dotnetspider.com/resources/18616-OOPS-Concepts-Net-Shake-your.aspx

http://www.dotnetspider.com/resources/18617-OOPS-Concepts-Net-Shake-your.aspx

http://www.dotnetspider.com/resources/18618-OOPS-Concepts-Net-Shake-your.aspx

http://www.dotnetspider.com/resources/18766-OOPS-Concepts-Net-Shake-your-funda.aspx

Feel free to bug me if something is not clear or if you want to know more....