Like they say... IF IT AIN'T BROKE, DON'T FIX IT!
but to whom are you talking
MS or the end users ?
Should the end user just keep on using it until it finally stops running having been taken over by a virus +
Heck if all it is being used for is a backup computer should anybody care?
Is it going to act like typhoid mary and spew its germs to all who come in contact?