Cisco 1801 Port Forwarding

I've just upgraded our router from a basic 3com OfficeConnect DSL Router to a Cisco 1801. I have run through the initial wizard and have a connection to the internet, and get outbound access ok, but am struggling to set up the NAT rules to allow forwarding of PPTP VPN traffic on one of our public IPs to the internal Miscrosoft ISA server. I need help getting the NAT rules setup, and advice on whether I should setup ACL rules? Currently I get outbound internet access ok with no rules setup, but not sure if rules are needed for inbound forwarding of the PPTP VPN traffic. We have a block of 16 public IP addresses from our ISP. Our internal network sits behind a Microsoft ISA Server (2006 EE) which is the only machine connected to the Cisco 1801 router. I've attached a diagram to show this. I'll provide the current configuration file to the selected coder. I have the basic 1801 with no firewall etc. ## Deliverables Require a fully working configuration file that fixes the port forwarding problems detailed above, with ACL rules if required. ## Platform Cisco 1801 (basic version, no firewall etc). IOS 12.4(6)T5. SDM 2.3.1