While configuring an X-Server, there is the possibility to turn off the caps lock key and use it as control key insteed by adding
Option "XkbOptions" "ctrl:nocaps"
into the "Input Device" section in /etc/X11/xorg.conf. But Mac OS X does not have any xorg.conf for it's graphical interface. A way to perform the same configuration on Leopard is to use the system settings application. The "Keyboard & Mouse" tab contains a button named "Modifier Keys..." in the keyboard tab. This button will open a window that does allow to bind the keys "Caps Lock", "Control", "Option" and "Command" to different functionalities. Use this dialog to change your settings accordingly.