Accessing IIS website from Internet

Hi,

I'm new to Windows sys admin, so I beg for apologies up front.

I'm running Windows Server 2003 out of my house. I have a broadband cable
modem that has an IP address assigned by my ISP. I have a Linksys router
that sits behind the cable modem. The server sits behind my Linksys router
and is dynamically assigned an IP address by the router. In the router
configuration, I port forward all requests to ports 80 and 443 to my server.
I use DynDNS.org to manage name resolution for the IP address assigned to my
cable modem.

I want to serve up web pages from my server using IIS. I can't even access
the default.htm web page for the default web site from the Internet. I can
access the site internal to my network, but not from the outside world. I
believe I've set up permissions correctly, but any and all suggestions would
be welcome.

Thanks!