Yes, you can statically assign them two the two IP addresses you have. 
 E.g. you can only have one port 80 per IP address being forwarded.  So 
you will need either a second IP address, or you can do some DNS port 
forwarding tricks and stick the second server on port 8080 for example.

Simply set the second server beind a 1:1 NAT using your second IP address.

The problem you will still have is this:  If you set an interface to use 
a dynamic address as a static address it will not attempt to renew the 
lease, and someone else will get that IP address and your ISP will stop 
routing it to you.  An interface can only request one IP Address 
dynamically, that I know of.

Peter wrote:

>Is it possible to run 2 web servers (separate computers) both on port 80 each with its own IP
behind monowall? I'm thinking that I would need two WAN interfaces.
>
>Here is my situation; I have 2 servers each with about 10 domains and a mail server, I can config
the port forwarding to the mail server no problem and one web server / ftp server but how can I
direct traffic to the other server on the same port. 
>
>Currently I have 2 reserved IP's via DHCP each going to a separate firewall which inturn feeds each
server, I'd like to run 1 firewall and split the traffic. Is this possible or am I missing the
bigger picture.
>
>Any idea's are appreciated.
>
>Cheers,
>Peter
>  
>