I am not sure why you are trying to install Fedora 5 in your DELL 1520.

Dell is putting their machines out on the street with Ubuntu installed.

The Ubuntu site has directions which are cross posted on Linux Profiles 
on how to specifically install Ubuntu 7.04 on this machine. I do not 
know how this would apply to Fedora, but I would think that before you 
get too discouraged that you get the new version, preferably Ubuntu to 
install.

The post specifically mentions that you need to use an alternate CD to 
get a load. I also am wondering if your attempt to use wireless to 
access updates may be having an impact. If you have your Wireless locked 
down, as you should I do not know if the install will be able to cope 
with the encryption that is on place.That would seem to be enough to 
generate can't update messages. A hard wired connection would test that 
quickly

http://ubuntuforums.org/showthread.php?t=501195

http://www.linux-profiles.com/laptop-computer/laptop/40

I hope that is of some service. I have a Fedora 7 DVD and I suspect that 
some of the PLUGgers would have the Ubuntu that could be made available 
for you to use.

Harold