Many of his greats were on Universal, who've released a decent boxed-set:
Vertigo/ The Birds/ Rear WIndow/ Marnie/ Frenzy/ Topaz/ The Trouble With Harry/ Torn Curtain/ Psycho/ Family Plot/ Saboteur/ Shadow Of A Doubt/Man Who Knew Too Much/ Rope
There's also a smaller, and less impressive (but still very decent) set from Warners:
Dial M For Murder / I Confess / Stage Fright / The Wrong Man / Strangers On A Train / North By Northwest Vertigo received a restoration about 10 years ago, but the DVD release was non-anamorphic.
The UK release was anamorphic, but taken from the US master and 'upscaled'.
The US version finally got a proper anamorphic transfer in 2005 for
Alfred Hitchcock: The Masterpiece Collection, and you'd have to guess it (anmd the others in the set?) had a new HD master struck then.
Sadly, Universal will have to dedicate much of their efforts/pressing plant allocation to re-releasing their HD DVD catalogue on the blu(e) format, as well as keeping up with new releases.
Warner have said they're working on a Blu-ray of
North by Northwest for release either later this year or in 2009 (sorry, I can't remember which).
Steve W