Since nobody responded to me, I did my own testing. Basically I tried a bunch of different video cards. It seems that choppy animation is due to video cards and not a slow computer. I disabled my onboard video on my p3 650 above and tested a 64mb pci geforce 2mx400 and VJ work flawlessly. Animation was smooth even on the fastest settings. I tried an 8mb ati pci card I had and the jerkyness returned. So for video on the pci bus it seems that 16 or 32mb video is the minimum (I didn't have either of these cards to test).
I then tested VJ on my mame machine which has an 8mb ati Video Card and a duron 700. This time the card is an agp card. It ran smoothly again. So it seems that the added bandwidth of the agp slot and sharing of the system memory allows a lower card to run.
So basically if you want to run a slower computer with VJ use an AGP card or a 32mb pci slot.
Tomorrow if I have time I'm going to test on a 450 and 300 and play Limbo with VJ (how low can you go

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I will post the results.