Well my router settings are:
802.11 Mode - Mixed N/G (used to be B/G/N but I no longer have B devices in use)
802.11 Band - 2.4 Ghz
Wireless Channel 11 (used to be Auto but a neighbour's wireless is overlapping on Channels 1 and 2

)
Transmission Rate - Auto
Channel Width - Auto
SSID Hidden
WPA2 Personal TKIP & AES
Gamefuel
Auto Classification Enabled
Auto Uplink Speed
As for the rules I'm using the ones from the updated section from your sticky.
Advanced Wireless:
Transmit Power - High
Beacon period - 100
RTS - 2346
Frag - 2346
WMM Enabled
Short GI Enabled
Extra Wireless Disabled
WISH - Enabled with all settings on
UpNp - Enabled
Thats about it for settings I suspect there might be something wrong with System Link but I'll have to email xbox about it or see if their forums have any solutions.