Online Multiplayer Lag

[Mouseraider]

I have been searching everywhere on the net and haven't found and proper answers.

My brother and I just started playing borderlands online (not lan) and we can't seem to get rid of the constant lag in private games. Neither of us experience lag while hosting.
I have added the following ports in hope that we could get rid of the lag, but so far no luck.

7777 (TCP/UDP)
28900 (TCP)
27900 (UDP)
28910 (TCP)

System specs for both comps.
OS: Vista 64 bit
i7 950
6 GB DDR3
gtx 295
I have a 20/20 mbit connection and my brother have a 2/512

We both use zonealarm (windows defender and firewall disabled) and I have made sure that it does not interfear with borderlands and gamespy.

I would be greatfull if someone could help us fix the lag issues that we are having.

[AIR.Morden]

same prob here...every 5-10 minutes i got a big lag. no shootin,no jumpin, no runin is possible...its not a big prob. my made is on level 31 so we got no probs if only one is shootin. yeah...i really want to know how i can change it. thanks guys...

forget ...really same spec:
core-i7 920 @ 3,0
6Gb-DDR3 1333MhZ
vista 64 bit
1on1 16m+ intenert connection...