You'll notice under the Harddrives tap in WinUAE that there is an button that says "Add Harddrive", if you click that, a box will appear with a pull down menu and a check box called "Read/Write". If you click on the pull down menu, it will show all drives in the machine that contain a valid Amiga file system, if nothing appears, then WinUAE isn't recognising the file system on your old Amiga drives, hope this helps.