Russ:
Note that we adding this to the software very shortly. We did not expect that many users move from the standalone RiverCAD 2000 package (with FLX file format) to the AutoCAD platform. This will be in the next minor release.
In the meantime, if you still have RiverCAD 2000 installed, simply select File | Save As, and change the file format to "AutoCAD version 14 DWG". RiverCAD 2000 will save the file out and you can then load that into RiverCAD XP.
If you have any additional questions or need any further information, please contact me again.
Sincerely,
Chris E. Maeder, M.S., P.E.
Senior Technical Engineer
chris.maeder@bossintl.com