Yes, but on Episode III Anakin doesnt seem to turn to the dark side because he gets angry sometimes or lets his feelings control him.

The only reason that is put on Episode III for Anakin to serve Palpatine is the promise of:

"If you kill good people i will (try to) teach you a new power to save good people from death"

Thats it. THAT is the only reason. They even say it three or four times during the film. The ONLY reason for him to do evil things is so Palpatine teaches him new jedi-powers on his jedi-powers list.

So, its not really his choise, he isnt seduced, he is simply extorsioned/tricked into it.

Thats why everybody thinks, when Padme is dead, well, now he will tell Palpatine to stick his new powers up his ass, and hang himself. Since there is NO REASON for Anakin to keep doing evil things.

So, really? Darth Vader spends 25 years thinking "If I keep doing this EVIL stuff maybe, someday, Palpatine and I, maybe, we will start the process of talking about proability of investigating how we somehow can discover the lost knowledge of saving the person that is already dead"?