Redirect to another internal webserver

We have two webservers in-house. Both servers are running IIS 6 on Windows 2003. We have one domain name that we use for our company website. On a different webserver we have a web based application that I want to give access to from the outside world. The problem is that we do not have an external IP address available for the application server. So the internal address is 192.168.1.2 of the application server and the company website IIS server is 192.168.1.1. (for example) How can I setup a redirection on our website IIS server to allow access to our web application on the other server from the Internet? I hope I am making myself clear.

Update:
I am able to map a network drive on the primary website server using a username and password that is local to the application server. So I have a drive V: on the website server that goes directly to the folder on the application server that holds the web app pages.

Make yourself clear.

Internet -> IIS Server 1 -> IIS Server 2 -> OR

Internet -> ISA Server (Firewall & Caching) -> IIS Server 2 ->

Internet -->Website Server IIS6 --> Application Server IIS6

Right now when I am on my internal network I can go to http://192.168.1.2 in my web browser and the web based application will open. I know that an address of 192.168.x.x will not work outside of our local network. I want to be able to access the application that is on 192.168.1.2 from the Internet. So, from the outside, I want to be able to go to www.mydomain.com, then have a link on our company website that will point them to the application on the other server. I would like our visitors to stay within our same domain. I can add a virtual directory in IIS on the website server that points to the web folder on the application server. Am I going down the right path with a virtual directory?

If you have a separate dns entry for the 2nd application you could use host headers on the main server and have the 2nd domain get redirected to the 2nd server.

Or you could just identify a virtual directory in the main server and put some asp redirect that shuffles everything to the 2nd server.

Or if both computers are on the same lan, you could just let the main server be the only webserver using a virtual directoy mapped to the other server.

I think what I have to do is use a virtual drive in IIS on the primary web server that points to the application server. I'm getting an "access denied error" not a "page cannot be found". So I think that I might just have a permissions problem and not a redirection problem.