[ale] more on the IP/MASQ question, need help

[jj at spiderentertainment.com (jj at spiderentertainment.com)]

Ok, I give up, please help. 
This is what I got so far:

2 machines are windows, 1 is linux RH6.0(just installed)

Linux:
it has 2 network cards, both are working perfectly. 
Eth0 is connected to a cable modem via RJ45.
Eth1 is connected to the other two windows machines via coaxal cable.

Windows machines: work perfectly, they talk to linux(ping, telnet, etc)

can not ping anything on the net. 

Can ya help ?

Thank you.