Wind speed and direction displayed on the ND are not accurate on the ground or the air for the following reason.
When the IRS is set up you tell it where it is, the IRS knows the TAS and heading and time flown and therefore knows where it should be in relation to where it started. The difference between where it thinks it should be and where it calculates it actually is it assumes is due to the wind. This vector is displayed as the wind on the ND.
This would be true if the IRS did not have any error of any kind; however the IRS does have a drift error. The drift error is added to the position error and is displayed as a wind on the ND. Normally this is very minor but it also explains why you may see 10 kts groundspeed on the ND when sat on the stand with the parking brake set.
Apparently new aircraft will have a wind on the ND derived from GPS data so the error will be negligible when compared to that derived from IRS data.