Forcing Media Player to Sync in MP3 format

Hi

I am running media player 10 on win xp Sp2

I plug in my new sony/erison phone that creates a drive on the computer.

Unfortunatly the Auto conversion option see this as a windows drive and
convert the MP3 to wma format. Which my sony/erison can not decode. I know
that I can turn off the auto conversion but this means I get the high quality
files copy to my Phone and reduces the number of songs I can store. I want to
use the Sync feature of reducing the quality.

If there a way to force media play to sync in MP3 format, to a drive.

Thanks for any help
Craig