Well the good news is that I finally got the new Hard drive to work, with sound and wireless. I was looking at interrupts and reloading all the drivers in Device Manager when suddenly I got a message that the wireless card had been recognised and the driver had been updated!
Since then I have been updating all the Windows files, loading new copies of antivirus, openoffice, zipper etc and am very happy with it so far. Good sound, good internet, clean and fast. I will try to get the old hard drive erased now and will use it for storage or backup.
I greatly appreciate all the advice and help I got here.

You can contract to Dell custmercare ................