Routing problem

[jb701@uku.co.uk]

I cannot get my linux box to act as a router, I'm hoping someone can help. 

My setup is sarge on a machine with 2 NICs, 192.168.1.2 and 192.168.2.1. 

I attach 192.168.1.2 to another machine with 2 NICs [192.168.1.1 and 
192.168.0.6].  This is a Win2K machine, and it routes connections from the 
linux box to other machines on the 192.168.0.0/24 network. 

I now want to attach another machine [192.168.2.2] to 192.168.2.1.  This 
machine [192.168.2.2] can ping either NIC in the linux box, but it cannot 
contact machines beyond it. 

I have used echo 1 > /proc/sys/net/ipv4/ip_forward.  Made no difference. 

I have tried using iptables but from what I can tell, I should not have to 
use that - the linux box ought to forward packets anyway.