mine does autoplay too, i think that might be windows media player auto-syncing your ipod to your WMP library (turn it off in WMP)
do you have the newest itunes installed? can you see the icon in the taskbar after the noise is made? usually it pops on the taskbar as soon as the pc recognizes it/noise is made.
try looking in 'My Computer' for the removable storage/disk too.
if nothin else works maybe its a defective cord or even ipod