Set AbelCam to operate on some port that the 2008 server is NOT using (lets say Port 9333 for this discussion). At the router, forward 9333 to the AbelCam machine. Job done. Now traffic to "YourStaticIP:9333" goes to AbelCam and traffic to "YourStaticIP" (no port specified) goes to the 2008 server like always.

I know nothing about the guts of IIS (I'm an Apache guy) but if IIS can do it then Reverse Proxying is another approach. Speaking in Apache terminology, what I do is configure mod_proxy to reverse proxy all requests for "some directory" to the AbelCam webserver. For example... if the AbelCam machine's internal IP is 192.168.2.2 and for "some directory" you choose "/cameras", the config looks like:

ProxyPassReverse /cameras http://192.168.2.2

Result is that http://YourStaticIP/cameras pulls up the main page being served by AbelCam.

You can see some of this working by visiting my site (http://eeberfest.net) and looking at the page source. The pages themselves are served from a Unix box in San Francisco. The video streams are served from AbelCam on a WinXP box here in my house in Los Angeles and they are passed through an Apache box (reverse proxy - also in my house) for extra level of security. In the source you will see paths like "eeber.no-ip.org:9334/abel" or "eeber.no-ip.org:9334/java". "eeber.no-ip.org" points to the outside (public) IP of my cable modem at home. ":9334" indicates I've got my router configured to forward Port 9334 to my home Apache box. "/abel" and "/java" look like directories on the home Apache box but are actually reverse-proxied "aliases" for things that come from the AbelCam box.