I have this:
http://img413.imageshack.us/img413/5046/whatiwant.jpg
Each list is its own WrapPanel and they are all on another WrapPanel which is in a ScrollViewer. If I don't set the height myself for the main WrapPanel it assumes I want the WrapPanel as high as it can go giving me only one column whereas I want as many columns as needed to fill the window.
atm I have just set the width and height of the WrapPanel that holds everything to fixed numbers, but I want it to change when the user resizes the window.