Sony Ericsson provides a free software to transfer music to your mobile device called Disc2Phone. But for Disc2phone to detect and recognize the mobile device and the memory stick duo card inserted in the phone, you need to change the USB settings on your Sony Ericsson phone to ‘File transfer’. Else it will error out saying “You must Insert Memory Stick or Connect your Phone with USB”.
To do this, disconnect your phone if it is connected to the desktop computer. From the main screen of your Sony Ericsson mobile phone, go to More–>Connections–>USB and then select ‘File Transfer’.
Reconnect the device to the computer. Disc2phone should recognize the hardware and allow you to transfer music and that too at a good speed.