What SkyWay said, it would be completely pointless to spend computing power on that. The edges aren't visible anywhere except if you look at the normal map itself.
Check the recommended landscape sizes. 513x513 is a heightmap size which will work for the old terrain system (power of two +1); for a landscape try 505x505 instead.
wow this look realyl powerful. just tried it and got the following. Error$8 : file or folder does not exist Line:o -> ~include contstants.jsx Is this a cs2 problem?