ipod touch 3g data+/data- sync behavior?

[dvd]

does anyone know how the Ipod touch 3g sync behavior works? i get an unknown device message in win xp, so it is not recognized properly. there are some sort of power issues or..?

how does the voltage pin connection work? on the usb end you have the 5 volt and data+/-, but what voltage on which pins is needed so that the ipod connector properly recognizes that it is connected to a computer and ready to sync?

does it need any voltage to activate sync mode/make it visible in windows? i mean, if i take an extension cord and just take out the 5 volt power lines and only connect the data+/- would that be enough (probably not...).

i found some information of converting a usb cable to make a charger cable (putting 2.8 / 2 volt on the data pins), but i am trying to get the syncing to work. without it, i cannot get any music onto it....