Networking :: Why Doesn't Distro 9.0 Setup Work For 13.1 Distro?

I have a linux box set up as a multi-purpose server for my home with three Windows client PC's. The linux box is based on a slightly modified Slackware 9.0 distribution using Linux 2.4.20 and an unfortinately old, slow AMD processor with a miserable 512Kb RAM. The linux box serves the CIFS file system to the Windows boxes, runs the SQUID HTTP proxy, the Apache web server, a print server, does masquerading, mail serving and a very effective firewall using iptables.

This system, although slow, has run perfectly for several years.Let me say that again - This system works perfectly.I had decided that now is the time to upgrade the hardware, so I bought a Gigabyte LGA775 motherboard which has two 1Gb network interfaces on it, an ASUS 256Mb PCI-E display card, 2Gb of DDR3 RAM, an Intel Core2-Quad processor and a bunch of 500Gb SATA drives to set up a RAID5 array (but I intend that the system boot off one of several 40Gb PATA drives I have).I set up the processor, motherboard, display card, RAM, a SATA DVD Drive and a 40Gb PATA hard disk in a "breadboard" layout and installed distro 13.1, being careful to set up the static IP for the local network, dhcpcd to get an IP address from the cable modem (my internet connection) and to enable ip_forward in the network configuration.

Then I installed a script invoked by /etc/rc.d/rc.local which installed all the SAME iptables rules as my old Linux box. There was one minor glitch when I had to change 8 occurrences of "-d ! $LOCAL_NET to" "! --destination $LOCAL_NET" but that was no problem. I also set up /etc/resolv.conf, /etc/hosts , the BIND server files etc. etc. exactly as in the old box.

I am able to ping mirror.aarnet.edu.au (this is at the heart of Australia's internet hub network - if it's down the whole bloody thing is down) and have the system find the correct IP from the designated nameservers and contact that server with a return trip time of 35ms. I am able to run a telnet session from one of the Windows boxes and edit files on the Linux server. So both network interfaces work and I've got them the right way around.I am able to run FTP on one of the Windows boxes and connect through to mirror.aarnet.edu.au, although it seems to hang when I try a DIR (but then so does the old linux system).