Little update:
I was able to get 1000 connection, after switching from AP to Auto and back to AP and then powering off for 20s and back on. Connection lasted about 20-30 min during which I started streaming video from the net. After this 30 min connection dropped to 100. So I did the whole on and off thing above again, connection is at 1000, this time I'm not doing any streaming, we'll see how long it will last.
EDIT: 2009/01/21
Well, connection seems to be holding, sometimes I need to force 1000 on the PC (autoneg will end up on 100 after wake from suspend), but somehow, it's working, which don't quite understand why or what makes it drop/go back up in a first place ...