All,
You can prevent CD's autoplaying when inserted. The options are: -
1) Hold down <shift> as the CD tray heads back into the drive from where it came (and long enough for Win to realise there is a CD in there) - This has been covered by Saab Dastard above...
2) Download TweakUI from the Microsoft Website and then in the options, use the "Disable autoplay" feature.
Best advice is always to leave the registry well alone unless absolutely necessary, as it can have dire consequences for the poor user if they get it wrong
Regards,
Shuttlebus