quick question. How come fallout 3 has not achievements on steam (pc)? there are on NV and fallout 3 xbox. is there a plan adding them on steam ? im just wondering.

Fallout 3 wasn't designed for steam in the first place? I don't know that's my guess.

Bwcause Fallout 3's achievements are tracked via Games For Windows LIVE instead.

Fallout 3 is not a Steamworks game unlike New Vegas. As said, achievements are gained trough GfWL, which means you have to be logged in to that to gain them.