Improving accuracy

I've noticed that the accuracy of my Garmin Foretrex 201 can be way out, based on the overlays with aerial photos. I mainly notice this when I use it for running (not sailing) and can see the track diverge from the path or road I was running on.

What setting can i use to improve the accuracy of my GPS?

Decrepit is correct about GE but the GPS may also be suffering from poor reception and low satellite count at times, especially if you pass underneath trees and even more if they are wet from dew or rain. Those things will cause track-points to wander off quite a bit.

Not much you can do about that really except getting a GPS with a better sensitivity and reception. There are whole forums dedicated to this sort of mapping testing and comparing GPS loggers and receivers so you could start with that of it is important enough to you

Have a glance around here: www.gpspassion.com/forumsen/default.asp

Oh, one thing you could try would be to wear the GPS on the top of your head. It should get a bit better reception there.