If you are recording w/ Fraps outta the film viewer, it's gonna be a bit jumpy if you don't have a fairly decent cpu.  Video work is a huge burden on a system.  I have a 1.5 GHz P4 & mine are always a little jumpy.  Also, turn off as many non-essential processes as possible to take some load off the cpu.  Defraging your harddrive prior to starting a video project also will help w/ the studders.