Thanks WildBill,
only prob im in Zambia so don't have the the land based transmitters to use with a differential GPS.
So i read that the GPS is accurate to 5m. i also have an idea of how the gps works but does anyone know what tipe of accuracy i will get with a moving tractor? could i expect to get the tractor to follow a line within like 2 meters? or 3? if i make way points 7 meters apart will that mean the way point can move like 5 meters more?? or could it be pretty stable?
plz anyone with some experience help 
regads
w