>How can two or more developers work on the same project shared on a network without getting "file access denied"?

You can use a product like MS Visual Sourcesafe. For only two developers, I think it's easiest just to coordinate work. Have one main copy of project on server, and each developer copies the entire project to local drive, where they do their separate development. When one person is ready to upload some work, it's copied to the server, and the other developer is notified...