Massive Packet Loss - Games Unplayable DSL

Hi all,

I have a whopper of a problem. First, some specs

Internet Connection

ISP: Telstra Bigpond (Australia)
Interleaving: Off (both on and off tested)
Type: "ADSL2+"
Speed: 20mbps (advertised), 16.5mpbs real world (speedtest.net)
Ping: 14ms (pingtest.net) 15-30ms (games)
Jitter: 1ms (pingtest.net)
Central line filter to 7 phone sockets
Two phone lines, 1 for DSL+Voice and one for alarm/fax.

Network setup

Modem/Router: Netgear DG834
Wireless Router: Netgear WG602
PC1 (WirelessG): Sony VAIO Z37GD | Win7 64 P | C2D P9600 | 4GbDDR3
PC2 (WirelessG): Sony VAIO Z46GD | WinV 64 B | C2D P9800 | 6GbDDR3
PC3 (Hardwired): Custom | Win7 64 HP | C2D E8400 | GTX260 SLI | 4GbDDR2
PC3 (Hardwired): Custom | PD | 1Gb DDR2 | WinXP HE | Not in use
Mac1 (WirelessG): Macbook 13 | OSX SL
NAS (Hardwired): Generic
Printer (Hardwired): HP All in one

Problem

Download speeds are fantastic. Ping is fantastic. I can command line ping any website and lose no packets.

However, in any game, lag is horrendous and completely unplayable, when connecting to any server, on any of the above computers, at 60+ FPS. Source Netgraph 3 shows a Loss of 80-83%, occasional choke, and a total up/down bandwidth of about 4kb/s. Server list load times are glaciel.

Ping trace usually shows a good ping with no packet loss until an arbitrary point in the list, where it says '100%' packet loss. There is no loss reported after that step, and no loss reported at the final destination. However, this is not always the case and I have ping traced some game servers and found no packet loss, even while simultaneously playing with netgraph 3 showing 80% loss!

What I have tried

ISP support - Useless (surprise)
Replaced the modem/router with new one
Tried individually connecting each PC by hardwire to the modem/router with all phones in the house disconnected
Restarted router 100 times!
Turned interleaving on and off
Tried double filtering the DSL line

For the love of god help me!