For the first part, about the motion paths, thanks, it is working now, which helps.

As for the second issue with the graph editor, my specs are fine. Or at least should be. I have an ATI Radeon 9600 XT 128 mb, 512 RAM, 2.5 GHZ AMD processor, haven't had any problems with it before. I dunno. All I know is that when I use the middle mouse button to move a keyframe, say on the Y direction graph, nothing is updated in the viewport, for any type of graph. I dunno.
Thanks for that, anymore suggestions would be appreciated.

David