Routing with the latest Windows XP Mapsource version and Ireland.osm from Geofabrik.de (03/09/2009) built with mkgmap revision 974 works fine ! "Chapeau bas" to all the developers. Now routes respects oneway restriction on motorways and round about. To obtain this result I use the splitter on the file. The result is a osm file size divided by 2. Thank you.