About file security???

this is what i wanna do... (any comment or suggestion are welcome, or anything that seems to be similar to what i want)...

i let my friend copy files from my computer, but i dont want them to spread the files to their friends or family (i dont want to beg for them and say please dont share this file...)

here is what i want to do... is there a way wherein if i copy the file through their usb drive, the file will be ''sort of protected for sharing''... like the file can be open, and deleted BUT it cannot be copied to another computer or another usb...

pls help??? tnx in advance...

About file security???norton antivirus 2007

i dont know how you can do that but i know how to password protect it. use winrar compress it then while compressing go to the advanced settings and put a password on it so that it can only be viewed with the password