For those on older computers, or who don't need all of Konqueror's features, or who find that their file manager settings in Konqueror interfere with their browser settings (or vice versa), or simply those who want a KDE 4 preview, here's how to substitute the light-weight Dolphin file manager as your file system default over Konqueror.
First, install Dolphin using the command line, Synaptic, or whatever method you prefer.
should work just fine.
$ sudo apt-get install dolphin
Then, open KControl (or your KDE configuration tool of choice. Using Pardus, mine is Tasma, but all are equal in this respect) and navigate to the File Associations setting. It may be under the Desktop section, but again, this depends on how your KDE is set up.
In the main chart, titled Known Types, expand the inode category. Select directory, and under Application Preference Order, click "Add." You only need to add this if you don't already see Dolphin as an option. Here, either type in "dolphin", or navigate to it in your virtual KMenu, under "Known Applications." In my case, Dolphin was in the System menu. It should automatically become your top choice under directory, and if it isn't, click "Move Up" until it is.
If you already had Dolphin in the Application Preference Order menu, simply click "Move Up" until it's your first choice.
Repeat these steps for inode>system_directory as well, and Dolphin will be your default file manager! To revert to using Konqueror as your file manager, simply go back to these menus and move Konqueror to the top, over Dolphin.