Thanks for the reply. I ended up figuring it out last night before this topic was approved. The problem is that I was making the assumption that a dstnat chain needed to be setup on the IP>Firewall>NAT tab so that I could set the port forwarding with rules on the IP>Firewall>Filter tab. In reality, the port forwarding rules go directly on the NAT tab without having to setup an overall dstnat chain. So simple, yet I over looked it.
So in short, the problem existed between the chair and the keyboard.
For anyone who may be in the same boat with this, the solution is actually very easy for a dynamic IP.
Once you have your router setup at home passing packets, doing source NAT (should be in there by default, at least it was on my 450G), and handing out your preferred DHCP address, do the following:
a) Command Line
Select a terminal in Webfig or Winbox
Enter the following command with your ports and IPs:
/ip firewal nat add chain=dstnat dst-port=<PORT> action=dns-nat protocol=<tcp/udp> to-address=<INTERNAL IP> in-interface=<NAME OF EXTERNAL INTERFACE>
If you have the NAT tab open, you'll see the new rule pop up.
Now I was trying to setup port forwarding on port 80, and using the example in the manual it does NOT specify an in-interface so it will forward ALL port 80 traffic from any interface to the specified IP. Not good since it will keep any other computer from browsing the web over port 80.
Key point for dynamic IP is to specify the in-interface (the name of which can be found on the interfaces menu. By default, my external interface is "ether1-gateway")
If you wanted to use the GUI:
1) Go to IP > Firewall and select the NAT tab.
2) add a new rule
3) find the boxes to enter the info contained in the command line setup above and lordkappa's graphics above
Whew. All that to figure out the problem was me.
Out of curiosity, if you're in the same boat and this helped you with your dynamic IP port forwarding setup, please post a reply. Maybe I'll post this into the Wiki if I find I wasn't alone.