This thread is seven (7) years old and things change. Not all files can be found by going to ftp.dell.com anymore (although they are still there, they are just impossible to find in their folder hierarchy).
You can use one of the following FTP browsing pages, or you can go to http://support.dell.com/ and do it the "usual" way:
http://ftp.dell.com/Pages/
http://ftp.dell.com/Browse_For_Drivers/