but in Fallout NV (can't remember FO3, too long ago), whatever you will say are complete sentences in the dialogue box, you just have to read through option and becareful with it (if you don't read carefully you might make the wrong choice).
honestly I like FONV's dialogue better. Oblivion's dialogue is a joke... for 12 year old kids.
sigh why are kids allowed to play games anyways :/