NAS File permissions/lockout query

Hey there

My small network has files stored on a central network hard disk, which is installed as e:\ . NOT MAPPED AS E:\ because its not a shared network folder, its an actual physical network attached storage.

I want to allow microsoft outlook 2003 to point to a folder on this drive so that every computer can access the same email folders, but there is no way of ensuring that only one computer can access the folder / file at one time.

How do i allow xp pro to set file permissions on the file/folder in question which is stored on the e:\ drive?

Thanks in advance

p.s: How do i enable net send on xp pro? and is it advisable? because i remember the messenger popup spams used this service.