You know what there really should be? An all-Hitchcock TV channel. Until that glorious day arrives, there's The Complete Hitchcock at Film Forum, running through March 27th. (The affiliated complete screening of the Hitchcock-directed TV episodes is at the Paley Center.) This weekend, we caught the double feature of The 39 Steps and The Lady Vanishes, two films in which Hitchcock's familiar concern with innocent people caught in a menacing and mysterious situation meets up with historical circumstances --- namely, the looming European conflagration. Both movies are delightful, intelligent entertainments, but our preference was for The Lady Vanishes, with its gripping conceit and flawless tonal tightrope-walking. Who wouldn't want to see that 24 hours a day?