Hello Dear;
the first thing you must know is that the fedora is not very good distibution to work in professionaly; i refer you to use the redhat 8.0 or better to use slackware 11.0 or 12.0.
ok now try to connect the internet directly to your fedora box and connect the client with an cross-over cable to the other ethernet card of fedora box. now test again.
if there is no resault; check the iptables mangel table if any:
iptables -t mangel -L -nxv
it should have no entery in.
Now you must check your squid.conf file.
i think there is a problem in your squid configuration; see this configuration about squid 2.5 in my site:
http://www.00p00.com/pages/RH/Cache%20Server.html
and compare with yours but its some different in 2.6 configuration only in transparency; like http_accell section. you must specify they in other place.
But the best way to test the squid is to disable it and trying again.
GOOD LUCK
mehdi.sadighian@Hotmail.com