Okay here are the specs for the computer it was running on (which is as you guessed one of my old clunky ones), to help you out, I'll make an FS9 vid of it too, I suspect it will run better in that, haven't tried it on my Vista PC either, it would probably be smoother on that one too, but the movie was made on this:
Intel Pentium 4 530 Prescott socket 775 LGA 90 nm running at standard 1.4v at 3.00 Ghz. Motherboard: ASUS P5GD1
Clock speeds Core: 3006.8Mhz. multiplier x15. L1 16KB. L2 1024KB. Bus speed: 200.5Mhz. FSB: 801.9 Mhz.
Memory: 2048 Mb DDR @ 200.5 Mhz
Graphics card is a PCI-X ATI Radeon X800GT
Chock