This is Ridley Scott's 2003 director's cut of the sci-fi classic, which hardly needed improvement back in 1979, when it had its world premiere at SIFF. (That's right, its world premiere! Respect.) Heres what's interesting 27 years later: AIDS and ebola and SARS have given a whole new mortal resonance to Sigourney Weavers (disregarded) concerns about quarantine and infection. The bickering, class-divided shipmates reflect the movies origins in Thatcherite England. Theyre fractious proles in the service of a corporate overlord whose computer proclaims, All other considerations secondary. Crew expendable. NOTE: No 7 p.m. show on Thurs. (R) BRIAN MILLER.