How in the world can I find which bgl files contain KGSP, Greenville,SC. I want to use that new XML scenery thingy, but I don't know which bgl files to convert.CH

The fastest way to find relevant BGL files is to use Jim Keir's TMFViewer utility. I think it's available in the library.

Or use AFCAD 2, the properties diaglog box gives you the bgl file it is using.

AFCAD2 won't tell you all the files in use, though. Only the AFD files.