Then you want this program :
http://freecorp.free.fr/ENG/furysync.htm
It's dedicated to sub synchro, and actually for having used it i can say it's quite good.. Most of the time youll need to set timing for the first and last line, maybe one timing around the middle, and hop, you're synched.
The interface is a bit daunting, but there is a tuto (in french, but with screenshots, so not hard to follow in other languages).
http://freecorp.free.fr/furysync/Tutoriel/img0.html..
It's really much much easier to use than any other tools i know of. Only thing : it's restricted to .srt format (but well i guess this is not much of a problem
)