Storage Space Monitoring tool

[Yahoo]

Friends,

I created a storage space for my organisation. with two 160 Gb HDD, Its to save the mail backups and other shared files. I want to monitor that storage space. I mean, Some times Somebody copying bulk unwanted datas to here, like movies and songs in different locations. I want to know if a file is copyed to thos computer and also from where it is copyed ? ( i mean the ip address or location )

How can i do this ?

I expecting you valuble help

thank you