DUEL CONSOLE NAT OPEN, PLEASE HELP!

I put this in the tech support area but it seems nobody posts there.  I'll try here.

I have both PS3 and XBOX 360.  I also have Black Ops for both consoles.  I have been trying for hours to get both of them to have an open NAT type but nothing seems to work.  I always end up with one being open, and the other being moderate.

I have a TP-Link router model TL-WR841ND.  I have both consoles set up with static IP.  PS3 is 192.168.1.30 and XBOX is 192.168.1.31

I have followed the instructions at portforward.com

Specifically

http://portforward.com/english/routers/port_forwarding/TP-Link/TL-WR841ND/TL-WR841NDindex.htm

which is the page specific for my router.  From this page I have clicked "Playstation Network" under P and forwarded all the necessary ports (80,443,5223,3478-3479,3658).  I also clicked "PS3 Call of Duty - Black Ops" under P and forwarded all the necessary ports (81,443,2005,3074,3075,3478,5223).

Then I clicked "Xbox Live 360" under X and forwarded all the necessary ports (53,80,88,1863,3074).  There was a conflict when I tried to forward ports 80 and 3074 because they are already being used for the PS3, so I couldn't forward them.  I also clicked "XBOX360 Call of Duty - Black Ops" under X and forwarded all the necessary ports (3074,22728,33233).  There was another conflict here for port 3074 due to it already being used by the PS3.

As of right now my PS3's NAT is open and my XBOX's NAT is moderate.  Because the PS3's is 192.168.1.30 it is open.  Because the XBOX's is 192.168.1.31 (next number in sequence) it is moderate.  I seem to be able to switch them around by switching the last numbers of their static IP addresses.

Is there any solution for my problem?  Hopefully one that doesn't include buying a more expensive router?