SAMSUNG T619: Make my own mp3 Ringtone

Finally, it works. Make sure your data cable is "Real Data Cable", not just power cable.

On Quicktime Pro:
Open file/[audio file].
Export file/movie to 3gp
In the dialog window, Select Audio tab.
Audio Format - AAC-LC (Music)
Data Rate - 64kbps
Channels - Stereo
Output Sample Rate - 44.1khz
Encoding quality - Best.

On Samsung PC Studio:
Get into Media management.
Select all media. Right click on frame and select Get From PC..
Choose 3gp file and import into phone.

On phone:
menu/fun & app/my sound/music/.../set as/ringtone

DONE!