the question is "do you have a policy for in place for these activities"?
If you do, what does you policy say about downloading / uploading music, files, and pictures?
do you have one for social networking? On the verbal did you document it via follow-up email to employee about the meeting and the resolution?
would you like a copy of our policies? if you don't have one, but want to put one in place. You can send the policy around as an ademdum to your handbook, be sure to have employees acknolwledge receipt of the ademdum. going forward have the policy as a part of your handbook.