I changed my rules to these:
/sbin/iptables -t nat -A PREROUTING -d $WIN_EXTERNAL_IP -j DNAT --to $WIN_INTERNAL_IP /sbin/iptables -t nat -A POSTROUTING -s $WIN_INTERNAL_IP -j SNAT --to $WIN_EXTERNAL_IP
And I am still not seeing anything log on the firewall log and the connection is not working.
I don't believe you need the forward rule since you're doing NAT. What does your entire NAT table look like?