Im in over my head, and i need some help!

[#1]

Chaps,
I'm having issues getting two Xbox's to share the internet connection so we can play online together. Ive had it working intermittently, but it takes a reboot of the router to get the NAT addresses to stop conflicting. Ive played with DMZ and UPNP to get the router to do all the work, with occasional success.
Now the confusing bit. There are three of us in the house, all using the internet and im certain the problem lies with the way im sharing it (badly).
I'll try to explain:-
Main BT Socket - Netgear NG834PN Wireless ON
1 Ethernet cable plugged into port 1 and travels to a Belkin G+ MIMO Router (not ADSL) Wireless ON
Confused yet? You will be...
The Netgear Provides Wireless for: 1 Playstation 3
                                                                1 Xbox 360
                                                                1 Laptop
                                                                1 Workstation PC
The Belkin Provides Via Ethernet for: 1 Workstation PC
                                                                  1 Xbox 360
                                                                  1 Playstation 3 (hardly used)
We have 3 iPhones that connect to both the Netgear and Belkin. Although the Belkin Wireless drops a fair bit
I prefer my Xbox Hard wired into the router as i find Wireless signal fairly unstable, so the second router seemed a good option. I have no idea what impact its having on quality of Data Tranfer!
Please Help, i really want these 2 xbox's to run together!
~Paul

[#2]

have you tried giving the xboxes different static ip's?

[#3]

Do you mean NG834PN? I can't find anything on that, maybe you mean DG834PN?
If you mean the latter, can't you just plug in the hardwired devices into the Netgear's ports, and take the Belkin router out? Why do you need the Belkin router?

[#4]

You should reduce the size of the DHCP range in whichever device you have assigning IP addresses, then assign static IP's to each fixed device, outside of the DHCP range but inside the /24 range.
E.G.:
Router 1 assigned static IP 192.168.0.1 assigning IP's via DHCP in the range 192.168.0.50 - 192.168.0.255
Router 2 assigned static IP 192.168.0.2 configured as an access point
Xbox 1 assigned static IP 192.168.0.3, default gateway set to 192.168.0.1
Xbox 2 assigned static IP 192.168.0.4, default gateway set to 192.168.0.1
etc.
I hope that makes sense!