Multiple Websites With Whs 2011?

I run my own web development company as a side project to my main job. I used to have some demo sites set up but due to a hardware failure these have been unavailable for a while. I have now set up a PC to host some of these sites but I don't know how to configure it to work along side WHS 2011.

I have a Virgin Media SuperHub, which has a CAT5E cable running to a DLink switch upstairs, which has the WHS 2011 machine, and the web server attached via CAT5E cables. because I have a dynamic IP, I am using DynDNS on the web server to provide me with a domain name for my websites. currently, when i type in this domain, it takes me to my windows home server login page. I assume that somewhere on the router, i need to forward ports to my web server, but when I do this, the WHS page stops working!

Ideally I want my router to forward ports to my web server, and then any requests for my WHS machine are passed on to the WHS box. but if it has to be done the other way around then it doesnt matter. I am not to worried about the domain i use either, but as i said, i would like to use my domain rather then the WHS domain.

my WHS 2011 setup is on a HP ProLiant 40L, and my web server is currently on a Dell Optiplex GX260 running Windows Server 2008 32bit (NOT R2!). The demo sites run on IIS 7.5. Any ideas?