As it happens, I just did a Vista software upgrade via the Internet today and it turns out that one of the upgrades is the "GPS Accuracy" indicator. Software versions below 2.50 didn't have it, so check your unit to see what version you have. If you are below 2.50, that will be why you don't appear to have it. (Or you MAY just be thick- I don't know...). Anyway, if you do the very easy upgrade, you will pick up this feature and from there, the instructions that Prime Suspect gave you will be dead easy to follow! Good luck!