I do video editing too, and from my experience and from what I've read, the GPU plays a letter role than does the CPU. If you are using an old Pentium 4, you're going to want to upgrade. Everything in the video/3D profession is shifting toward 64 bit computing. Try getting an Intel core 2 duo or i7 processor and coupling it with a moderate GPU if you are on a strict budget. Try the nvidea quadro series.