thanx janitha for ur reply
but look at this thread
Mp3 player with charger
redhat says that:
Re: Mp3 player with charger
The external AC Adapter can cause serious firmware damage.
I had bought one such adapter for myself, but during a 1 second voltage fluctuation, the whole firmware got damaged, I lost all my data and had to flash the firmware again. Using the USB Charger is the safest in that case
is he talking about another kind of charger or the same one i'm talking, AC to 5V USB adapter shown here :
http://www.semsons.com/acwalplugto5.html ?
i'm still confused

about wat to do?
if it doesn't work, i have to leave my plan to buy mp3 player

.