just delete the trash, file shareing apps and all, tell em you had a E-mail from the RIAA enquiring about file shareing apps at your place and you decided to remove them just in case, most of them will be so worried they won`t complain
, anyway the sods should be working, not downloading porn and warez, theres always some git from the office down the shop floor wanting more done in less hours at our place, about time these office bods did something for a living
Mentor.
ps: you could install loggers on all the machines and check what they where doing later,after hours, could be interesting
, and they shouldn`t be using works machines for personal use anyway.