An easier solution for me was to install the new Sony Ericsson PCSuite that now supports Notes 6 (and works with 6.5). After unsuccessfully trying all year to sync my Notes calendar with the P800, the new version works great. The sync software was released for the new P900, but I'm using it for my P800 without a problem. Get it here:
http://www.sonyericsson.com/spg.jsp?template=SP1_17_1&B=ie&PID=10101&FID=4854&LM=SD_V&FileCatID=4&MN=Synchronization&noredir=1