Is there a way to see what has been deleted and by whom...

I use this program called undelete. It will take the deleted file off of the server and put it into the bin, regardless of who deleted it. Ow and it will tell you who deleted it. Hope that helps.

Cool, Can you tell me who makes it?

Executive software.
Good Luck

Assuming you are using NTFS, can't you just set the permissions for the users so they are not able to delete files in that directory? Or do you just want to do that for one particular user and allow the rest to still delete?
What about auditing? That will tell you who's deleting files (assuming they do it again after you enable it).

http://www.bitmart.net/undelete.htm

Restorer2000 is a powerful data recovery software that can undelete files deleted accidentally in NTFS partitions, and can even recover data from formatted or corrupted drives.