Quote Originally Posted by Mindflare
I know my IP is right. There are no local firewalls on (XP or Fedora). I've got pretty good reason to believe that my ISP, Comcast, doesn't block port 80, since I've hosted on them before (no more than a month ago, too). No matter what port I use, it doesn't work. Apache is set to listen on port 80. Apache works properly, as I can see it internally, from all computers on this network. Just not from outside, over the web.

I'm about to give up, I'm stumped, and I guess the situation is a bit complicated.
I'm pretty sure that iptables is installed by default on pretty much any linux distro. Check that it allows non local IPs to connect.
Aslo, when you hosted a month ago, was it with the router in place?