>You are using SQL 2008 and your values sound to be UTM values. Then why don't you simply utilize SQL 2008's spatial datatype and its methods. For example your location is somewhere near Petit-Rocher. Using Petit-rocher nord and sud coordinates:
>
>

DECLARE @g1 geography, @g2 geography;
>
>SET @g1 = geography::STGeomFromText('POINT(-65.7142 47.7661)', 4326);
>SET @g2 = geography::STGeomFromText('POINT(-65.7305 47.7975)', 4326);
>
>select @g1.STDistance(@g2);

I get result as 3698.76 meters which looked right to me.

Thanks