Twenty-three years ago Don Siegel made his famous horror pic 'Invasion of the Body Snatchers'. Now there is a new 'Invasion', even more chilling than the original; make-up effects by the man who dreamed up the aliens in 'Close Encounters'; special sound effects by the man who 'voiced' R2D2 in Star Wars. Gavin Millar talks to star Donald Sutherland and director Philip Kaufman.