Automatic Sync Software

Hello everyone, I am looking for recommendations on software which will do the following:

* Users will save files to their local C:\ drive.
* Upon modification or creation of a file, the software will automatically copy it from the client desktop to our file server.
* If the user deletes a file on their desktop, the copy on the server stays put.

Basically I am looking for real-time synchronization software (which will run as an agent on the user's desktop I assume) which will not delete files on the client desktop if it detects a change.

We currently use SyncBack running from the file server, so it creates large spikes in network usage, and takes a long time to complete. We are looking to remove that "middleman" time and bandwidth issue between the desktops and the file server/tape archive.