Cannot get permanent admin rights to files on network drive

New computer came with Vista installed. I set myself up with admin rights but when I access files on my server they are opened as Read-Only. I can change the ownership by clicking the properties ->security and modify the file but when I access it a second time (after closing network link) I do not have ownership again. I have set the Run As Administrator and that has no effect - I even set up the hidden Administrator User. These are files that I had no trouble modifying, saving, creating, etc, when running XP Pro. My tech support people are advising that I roll back to XP. That is not an option.