For those of you with Flash-based players, what bitrate do you encode at for use on your MP3 player?

Currently, I am using 192kbps encoding, which allows about 50 songs on my 256mb iRiver 390T. I am considering re-encoding MP3s for use on my player to 128 or 96kbps. Will I be able to tell the difference between them all?

Thanks!

please note that you should always encode from the original CD for best results. I used 96-128kbps wma 9 (variable bitrate) and it worked. But my player had 128mb only

Well, that's a question only you can answer.
Personally, I wouldn't go below 128 kbps even on a flash-based player. I'd probably use LAME --preset medium if I were in your shoes, but if the artifacts @128 don't annoy you, you might as well cram a few more songs into your player.