Date Logic

I am trying to use date in my formula. What I want to achieve is =now() in one cell and create some argument that makes another cell move up every friday. so Current date is 4/16/2012 1:21am and deadline for the work to be done is 4/21/2012 12:00am. Every Friday at 12am I want the cell to show the next friday at 12am. when it is 4/21/2012 12:00am this cell should change to 4/28/2012 12:00am