Google Earth gives you the Lat/Long values in sexagesimal (base 60) while Google Maps uses decimal (base 10). The most obvious difference between the two formats is the use of degrees, minutes and seconds which has the form 30° 12' 01" instead of the more familiar decimal point 30.200277.

The easiest way to get the true decimal coordinates, go to http://mapmaker.donkeymagic.co.uk/, move manually to where you want to pinpoint, click in the spot and use the values given in the boxes on the left (to six decimal places) as the values for the Google Maps Action. Alternatively, to calculate your own you can use this formula (the value will be negative if the original sexagesimal value ends in W or S):

decimal lat/long = degrees + (minutes / 60) + (seconds / 3600)