I don't know about using neural net classification for soil mapping, but I might be able to help you get your raster into ENVI.  Do you know what format the raster is in?  Sorry, I'm not familiar with the format exporting options from within ArcGIS 9.2.  Is it an Arc GRID format?  If so, then you might want to try choosing the menu item File > Open External File > IP Software > ESRI GRID.  What did you try so far in ENVI, to read these data?  And what, exactly, happened? Peg

Thanks for your kind offer to help me. The raster file format from ArCGIS is AUX. I did try opening from the external file but to no avail. The only alternative that I had was to export the file as JPEG but all the projection parameters are lost then. Thank you for your kind advice. Tsheten

I'm not familiar with the AUX format, but I can tell you that it is not a format that ENVI supports.  JPEG format doesn't store map information.  Is it possible for you to save the file from Arc into a format that ENVI does support and that also supports full map information?  For example, GeoTIFF, or ESRI GRID?