I used to think fallout new vegas was horrible after I beat fallout 3, but it gets MUCH BETTER, after you actually get to new vegas.
I would suggest fallout 3 first, then fallout new vegas, because after you play fallout nv fallout 3 seems kind of lame in comparison.
They both have horrid stories compared to most games but they are worth it, and will provide hours of fun.
Also I disagree that fallout 3 has a better story, the stories are the same in my opinion on the, and half of the people here probably didn't even beat fallout NV.

(Before anybody posts I know nothing about stories I do, I play a whole bunch of older games just FOR their stories.)

Voted for fallout 3, not because it's better, but because you should play it before fallout new vegas.