Xbox 360 Internet Trouble

As some of you know, I haven't had a 360 for very long. I have not connected it to the internet before cuz I usually do my online gaming on my PS3, but I'm thinking about getting live so I can enjoy Halo, which happens to be my favorite FPS. So, to connect it to the internet I decided I didn't want to waste money on a wireless thingy and I'm not going to have a 100 ft ethernet cord running through the house because my mom would probably kill me for that. I know, she's a loonatic. So, I connected my Xbox to the internet by internet connection sharing. I connected an ethernet cord from my laptop to my Xbox360. The laptop is wirelessly connected to a router. When I first connected it, it worked right away, but there was a small error with the NAT. Here's exactly what I got:

You can connect to Xbox LIVE, but your current network configuration may limit your online experience. Select More Info for a description of the problem and how you can fix it. More Info:

Your NAT type is Strict. People on networks with this NAT type may not be able to join certain games or hear other people while playing online. For the best online experience, you need an open NAT configuration.

Suggestions:
1. Turn your router or modem off and back on, then wait 30 seconds.
2. If your router supports UPnP, go to your router configuration web page on your PC and enable UPnP.

I tried both of these suggestions. My UPnP was already on, so that is clearly not the issue, and I restarted all my technologies several times, so that has nothing to do with it. So, I looked online and I all I found was that it would be useful to open ports. So, that's what I did...I opened ports. Here's the ports I opened and all my manual Xbox Network Configuration Settings:

IP Settings- Manual
IP Address- 192.168.0.59
Subnet Mask- 255.255.255.0
Gateway- 192.168.0.1

DNS Settings- Automatic
Primary DNS Server- 192.168.0.1
Secondary DNS Server- None

No Additional Settings

Ports:

1. Xbox 360 Port 88-88 UDP on 192.168.2.59
2. Xbox 360 Port 80-80 TCP on 192.168.2.59
3. Xbox 360 Port 53-53 UDP and TCP on 192.168.2.59
4. Xbox360 Port 3074-3074 UDP and TCP on 192.168.2.59


So, with these ports opened I figured the problem would be solved because this helped many other people, but it didn't seem to do anything. I have no idea how to fix this NAT problem. It's the same error every single time. Could this be possibly because of the method I am connect through with my laptop, and is not fixable? Please, if anyone has any suggestions, ideas, help, or anything to offer with this problem let me know and leave a post. I would greatly appreciate it.


EDIT: I also saw on the internet that setting the DMZ on your router to the 360 can also help with the NAT problem. So, I set the DMZ to 192.168.2.59, but it completely disabled my computer from the internet and it gave my xbox an even worse error, saying the MTU value was too low even though it wasn't. So, I set the DMZ back and got the same error as before. Clearly that wasn't the solution, even though I was hoping it was since even my router gateway page said it was useful for NAT in gaming. So...I'm completely stumped and just waiting for a possible answer from you guys.