Password protecting folders in NT

I have a user who needs secure files. He has a folder on an NT server that only he and I can access, but, being extremely busy and hectic, he is constantly walking away from his workstation while logged on, which leaves his files vulnerable. I tried using a password protected screensaver on his machine to lock his machine after one minute, but the screensaver won’t start (a completely different topic). Is there any way to password protect a folder on an NTFS partition?