IPhone 2G Maps Question

hello everyone, my friend gave me his old iphone because he upgraded to the new 3Gs, i used to have the iphone 3g until my sister took it from me.. anyways. i was using the Maps on the iphone and does anyone know why the blue circle which is ur current location doesnt pinpoint your exact location with a blue dot like my iphone 3g does, yet it stays in a small blue circle... anyone know how to fix this. heres a picture




Thanks in advance.
-Mark