I'm having a problem sharing files.

I want to be able to read/write files from another computer on a local network. I've tried a few different configurations but can't quite get it to work.

The computer hosting the files is using OS 10.4. I've put the file I want to share in the public folder. I created a new user. I changed the permissions so that both the owner and the group can read & write the file. Also, from the pop up list for the group I selected the new user I created.

When I connect from another computer running OS 10.3 as the user I newly created I can open and edit the files. The problem is that the person using the host computer can also open the file and edit it at the same time so the changes on one computer end up not being saved. There doesn't seem to be any way to tell if the other user already has the file open.

If two clients try to open the file on the host at the same time, the second one to try to open it will get a message saying it is already open and that it can only be opened as read only. I would like this message to come up when the host and one client has the file open.

I hope this makes sense. I've been using Macs for a while now (although I'm certainly not an expert) but I never had any trouble sharing files until we upgraded to 10.4.