Hi to all fo you guys.
After 1 week of searching and trying different video converters I found this one:
http://iriverter.sourceforge.net/download.shtml
It is really simple and the video is quite good. Just what i was searching for my customers. I posted it here, maybe somebody else needs something like this.
Before converting your video just select H300 series device form this menu:
Options->Device->iriver
Greets