A fancy graphics card can capture video. A realtime card, like the RT.X100, can capture video AND speed up your editing by performing the special effects using hardware acceleration rather than use software-based rendering. The majority of my editing with my X100, including color correction matching videos shot with multiple cameras, require no rendering. The X100 also gives me realtime transcoding of the video for DVD authoring and some hardware acceleration in After Effects. A regular video capture card can't do that.