I have used the GeoXT extensively with aerial photography in the background, and I think it works fine. I did not notice any problems with resolution.The only disadvantage I have noticed is that you can have only 1 layer = background on the screen. You cannot display your air photo and last years data points while mapping a new layer. You may want to decrease file size by cropping to the air photo portion you are working with to decrease loading times. The problem is memory, the hardware, not software- and as far as I know the only way to get around this is using a full size table PC or field PC. Then you can run the ArcPad extension of ESRI - and use GPS receivers and GeoCorrect from Trimble. This gives you the full functionality of a GIS in the field: multiple layers, direct update of shape files, etc. I don't recommend running ArcPad on a Pocket PC, in my experience it is terribly unstable.
Sabine Mellmann-Brown Postdoctoral Research Scientist Montana State University Department of Ecology 310 Lewis Hall Bozeman, MT 59717-3460
