Since you don't have a second processor, I would only go to Jaguar on that machine if Carrara is unstable on OS9. I've had really good luck with the patched version on Jaguar, as long as I avoid the texture room. I've tried Jaguar on a machines that bracket yours in speed. 8.6 or 9.x will be much more responsive just on an OS level for these slower machines. But I have to admit that I use Jaguar on them because I just can't work in the old systems after tasting the good stuff.