What movie should I do?

There is one thing I'm stuck on, and thats what is a film opening?
Is it the first 5 minutes of a move before the film really starts, or does it specifically have to be a title sequence?
Anyways, heres a list of movies I love that I can refer back to anyways.

1. 9
2. 300
3. 500 Days of Summer
4. Burn After Reading
5. Clash of the Titans
6. Click
7. Eagle Eye
8. Easy A
9. G.I. Joe
10. Gamer
11. Inception <3
12. My Girlfriends Boyfriend
13. My Sisters Keeper
14. Robin Hood
15. Scott Pilgrim <3
16. The Invention of Lying <3 <3 <3
17. The Notebook
18. The Social Network
19. Zombieland

So wow, there you go, quite the list, ill work through them all so see if any of them fit the criteria,

Oh wait, i forgot, what is the criteria for a good opening.