1. 2001:A Space Odessey :rock:
2. Alien
3. Serenity
4. Logans Run
5. Silent Running
6. The original Star Wars trilogy, not the new abominations they called "prequels"
7. Brazil
8. Metropolis

Forbidden Planet
The Time Machine (Original)
2001 & 2010
The Andromeda Strain
Dune

In no particular order...

No particular order.....

Star Trek II
2001
2010
Blade Runner(Director's Cut-haven't seen the latest version, released last year, I think)
Empire Strikes Back
:)

A few more for good measure....
Silent Running
Soylent Green
Planet of the Apes(Original)
Aliens

:)

1. Solaris (the original)
2. Time Bandits
3. Star Wars: ESB
4. Alien
5. Zardoz-HA! Just kidding. I'll pick Brazil

Picking just 5 is tough.

Why is sci-fi literature so hard to make into movies? The only other lit I can think of that suffers the same trouble with translation (whether on stage or screen) is Shakespeare.

The Fifth Element
2001 & 2010
Dune
12 Monkeys - mind bender
Star Wars saga
Dark Star - funny as hell - bomb 20

Do TV shows count too or just movies?

1) Stargate (SG-1 and Atlantis)
2) Star Wars (all the OT, PT is only good for saber fights)
3) Alien, and Aliens. Those were probably the best 2 of the 4.
4) Predator, cheesy Arny movie.
5) Starship Troopers. Lots of blood and horrible military tactics offset by some fairly cool action sequences.