GOP means (G)roup (O)f (P)ictures. It is a way to refer to a family of video compression schemes that rely on not just single frames, but collections of frames to work. It is very computer intensive to try to edit that kind of footage.
What most folks do is to "transcode" or change the compression format of the material before they start to edit. Apple created a great format for this with another family of codecs (COmpressor/DECompressor) called ProRez. The problem that Jeff noted is that only the last versions of the G5 product line (Quad G5 towers) could handle the processing of that format.
I am not familiar with cameras, so don't know what comes out of your Samsung. Could you open a clip in quicktime, then under Window menu open the Inspector? That will list the tech specs of the clip. We know that it is h264, but what is the frame size, and frame rate?
What are the spec's of your computer? model, OS version, and Final Cut Version. With those details perhaps some the gurus here can make a more specific recommendation about what codec to use to edit and how to go about making the transcodes.
-Vance