i have heard that the ati raedon graphics is not so gud for playing games than the nvidia .is it actually true????
No, that's a lie. Read the reviews for your self. In any given price segment AMD Radeon and nVidia GeForce cards trade blows and it really depends on the game as to which GPU is best for you. One thing that is true is that current nVidia cards use more power than similarly priced Radeon cards.
Are you looking for a new GPU or what? What do you currently have?