Thanks for the input.
So far I've tried all the software mention here but none is so versatile as the iRiver plus 4 with the old AK120 that I have.
It's so easy with the iRiver plus 4 + AK120 in the past I simply drag and drop the music in the AK120 directly and create/edit/delete the playlist.
With those software mention above, I need to create the playlist in the computer and sync it with the AK240...or I'm missing something here.
After trying, I finally use the windows media player, create the playlist there (in the computer) and later on copy the playlist to my AK240 playlist directory, so far it works fine, not perfect but work nevertheless.
Hopefully iRiver issued their compatible software for AK240 in the near future, they should, for such an expensive and amazing equipment, little things like this really counts.