[dundee] iptables and fair network usage

[Nistur]

Ok, I've finally got around to unplugging the linksys thing and starting 
the compaq up again, I made sure all the modules were loaded, I flushed 
iptables and just added nat, I restarted dhcp server and I checked my 
computer. ping, I have internets.
I go to check someone else's PC and I don't get so lucky, it would seem 
that they don't get given a default gateway ip. I check with multiple 
systems and linux ones that were up before the router switch are fine, 
anything else is a problem.
I then start another linux box up and:
route add default gw 192.168.1.1
and it works.
I then try setting ip and dns manually on one of the windows boxes. 
Still nothing.
I check everything again, I ping router from each machine with positive 
results.
I then sit and look through google and find that I can set:
option routers 192.168.1.1;
in dhcpd.conf. I try again, still nothing on windows, my computer's 
still happily up, but other linux machines start dropping out, and 
setting a default gateway doesn't fix the problem.

Here is my complete subnet section of dhcpd.conf
# Flat network
subnet 192.168.1.0 netmask 255.255.255.0 {
        option domain-name-servers 192.168.1.1;
        option routers 192.168.1.1;
        authoritative;
        allow unknown-clients;
        range 192.168.1.100 192.168.1.200;
        }
Please please please can someone help? This is really driving me up the wall