Well it turns out I was not quite right – although upgrading the GPU to an 8400GS was a vast improvement, it is still not quite right. It seems that the CPU carries a bit of workload when paying Blu ray.The processor is running at between 60% and 100% during play back. And this is causing it to stutter slightly – enough to be annoying.
For the record the CPU is an Intel Pentium D 3066 MHz. So it seems that I DO need to upgrade my CPU
Which is a shame, becasue I really don’t want to. Although it does mean I can use the exisiting CPU in my yet-to-be-built home server….