New installation of Intrepid 32bit with Samsung scx-4200 usb plugged in during install; first thing I did after the updates was to install the Samsung scx-4200 print driver.
CUPS and its associated dependencies were already installed, scx-4200 was showing in Admin > Printing as a USB device but no driver listed - therefore didn't work!
Go to http://www.openprinting.org/show_printer.cgi?recnum=Samsung-SCX-4200
Scroll to the bottom of the page and downloaded the splix i386 .deb.
Click on the deb to install it and wait (and wait...!). Eventually a terminal pops up asking how to configure the default mail client (bizarrely). Type 5 (Leave configuration unchanged).
Installation completes, so close all opened install boxes.
System > Administration > Printing.
Click New printer (ignore the fact that the original scx-4200 is listed there). Follow through and select the newly added scx-4200.
Finish off by printing a test page.
Finally to tidy up, delete the old scx-4200 listing.