Nautilus opens a new window every time I click a folder. How can I change it back to the old behavior?

The new Nautilus uses a spatial mode, where each folder that is clicked on opens a new folder. Many people believe that this is an improvement in usability while others do not like the way that the new Nautilus works.
It is easy to revert Nautilus back to its old "Browser mode" by issuing the command below as the current user:

gconftool-2 --type bool --set /apps/nautilus/preferences/always_use_browser true 

You may have to log out, then back in again for the changes to take effect.
To change this back to its original behavior issue the command:

gconftool-2 --type bool --set /apps/nautilus/preferences/always_use_browser false

Nautilus can be further customized by using the "Configuration Editor" in the System Tools menu.