That is the same version of the PPD file that I got from downloading the Dell driver CD image.
Bruce is correct that most of the time, the PPD is all you need for a PostScript printer. In this particular instance, however, you will need to modify the PPD or use the Dell installer to install other software. The PPD that you have contains a line that calls on PDEs (printer description extensions) that need to be installed. Otherwise, the print job will fail and you will be told you need extra software.
If you don't want to install the Dell drivers using the Dell installer, you can simply delete the following line from the PPD
before you add the printer:
*cupsFilter: "application/vnd.cups-postscript 0 /Library/Printers/Dell/filter/DellSecureFilter"
Message was edited by: Matt Broughton