Couldnt find word for word what kijangnim has said in FCOM, however, since he's from France he may very well be right. I did however find the following which may also help the original poster
FCOM 1.31.45 indicates that current G/S only is used to give the ETA for the next waypoint shown on the ND.
This from FCOM 4.02.20 for FMS time/fuel predictions
"IN FLIGHT : The system updates the predictions and the current ECON speed, using the measured wind at the present position. It mixes actual wind and forecast winds to compute the wind ahead of the aircraft but this is totally transparent to the crew."
And this from 4.04.25
"Once in flight, the FMGS considers the actual measured wind up to 200 NM ahead of the aircraft to permanently update the wind profile. This updated wind profile is used to compute the predictions and the performance data, but is not displayed to the crew."
As other posters before me have already said, what I have cut and pasted here may be some of the reason for differences shown between ND and FMS predictions.
Edited to add some FCOM references
Last edited by waren9; 13th January 2009 at 21:05.