thanks, it all works now except that the more i increase the near clipping plane, parts of my airplane will dissapear.... and when i change the clipping plane from 0.01 (default) to 1, it improves extremely, and barely has any white lines left on the objects..... but if i increase it more, then it will just stay the same, no more lines will dissapear.....

The best way to adjust these parameters is:
- Adjust the fog intensity: the terrain should vanish in the fog at a reasonable distance; you must experiment to achieve the desired results.
- Adjust the FAR clipping plane so that the terrain won't be clipped before vanishing in the fog;
- Only increase the NEAR plane distance if you have problems with objects "buried" in the terrain. When you have objects which intersect with the terrain, the video card uses the Z buffer to decide which part of the object is visible. If the near plane is set too low (below 0.3), when flying you may notice the borders of these objects varying randomly while you move. This is caused by inaccuracies in the Z buffer, and increasing the near plane distance greatly improves its accuracy - but you may have the nearest parts of your airplane clipped, since nothing before the near plane is drawn.
The Z buffer values represent the distance of every pixel rendered in the screen measured from the near plane. A non-linear function is used to compact the distances in 24 bits (the usual word size for the Z buffer). This function is much more sensible at small distances - that's why the near clipping plane has much more influence on the Z buffer accuracy than the far plane.
Usually the best range for the near clipping plane is 0.3 to 0.5

Thanks, you helped alot :)!!!!!!

ok, i fixed the tree issue, but still i can't figure out how to make the terrain that is further away appear when you are not close to it..... :( ...