http://forum.ppcgeeks.com/showthread.php?t=23659
Take a look. The problem I have had with vista and sync is not the mobile device center, but the driver install for the PPC. Right click "My Computer", Get to "Device Manager" and uninstall the usb device for the Mogul (it is not in the usual usb device location). Use Killsync (or CTRL ALT DEL) to shutdown activesync on the PC and restart activesync manually then reconnect the device. Works for me.