The unit and HumminbirdPC will automatically show the zero after the .6 minutes. Just make sure that you select the ddomm.mmm format under the Edit – Preferences – Position Format menu. This may be the default for the HummPC program though. Too bad that you do not have them electronically as usually they can be mass converted and brought into HummPC a whole lot faster than typing them in.

Any idea which Map Datum that Greens Ferry map is using? If it is not the WGS84 map datum than those waypoints could end up being off quite a bit.