I am using DLink Media Server on Vista Ultimate x64 with no problems. I have to run version 1.08, as every version that has come out since immediately crashes when you try to open the GUI (On two other WinXP Pro PC's, an XP Home PC, and Server 2003). Since the DSM-520 is a redheaded stepchild, and they haven't put out any updated software in over a year, don't expect them to support Vista x64 anyhow.