Firewall with Reverse Proxy

I need either a software (ISA server) or hardware (router) solution to my problem. I have been using Novell's BorderManager firewall to connect my Win 2000 server to my DSL internet line. The problem is that I am trying to use Windows' host headers to have multiple URLs at one public IP address. BorderManager does not support this. It wants a separate IP address for each port 80. It does support the reverse proxy and NAT that I need to connect the windows machine to the DSL line via the Novell BM server. I currently am assigning different port numbers to each Web site. All traffic goes to the Windows server's default Web site. this is not a very good solution, since no one can go directly to a non default Web site without knowing the port number.