Port Forwarding Help

Alright, to start off with let me explain my situation.
I'm playing a game called "GunZ" which requires ports 7700-7800.
Well, it doesn't REQUIRE them to be open, but if they aren't - I get "NAT".

Pretty much I want to open ports 7700-7800 in order to bring pings down.
Since GunZ is using a p2p system, opening the ports should reduce pings by a lot.
Currently I am averaging around 120-140 pings with people from NA.
Even to other computers inside my network, I am only getting 90-100 ping.

So, people have told me to "Port Forward", they said after port forwarding they get around 20-40 Pings.
So, I have come here in hopes of some serious help.

To start with, I have already tried the tutorials on portforward.com
I've also contacted my ISP, and followed all of their instructions.
From what I understand that DSL Modem I have has a double NAT.
I'm not sure what it all means so that's why I am here.
Anyway, I'll describe my network.

I have a ZyXEL 660r ADSL Modem, this runs into my Router.
It's a Linksys WRT54GS Wirless&Wired + Speed Booster router.
Note, that I am running WIRED, and have the wireless only for my laptops.
Alright, so then I run 2 lines out from the router to my other computers.
My computer is the only one on the network playing this game.
So I need to dedicate ports 7700 - 7800 to my LAN IP.
192.168.1.101 <- assigned by my router.

Also, I should note that I have a DYNAMIC IP Address.
From what I have been told it's possible to port forward my network,
but they told me it would be harder to do without having a static IP.

Anyway, if anyone could help I would GREATLY appreciate it.