Sharing Files

I have an Excel file I would like five people to be able to share and insert data to. We are all on a LAN running NT. Here’s my dilemna: I need to have only one person using the file at a time to prevent others from opening the same file, editing, and then saving which would overwrite the other person’s input. Is there a way to allow these five people access to the file to put their input in, while at the same time, protecting it from each person overwriting the others and thereby essentially deleting their input?