Carrara 1 was, unfortunately, not very stable (very nearly, in fact, "broken" software.") It got patched up quite a bit when it became Carrara Studio, but both Carrara Studio 2 and 3 added a ton of new functionality across the board; subdivision surfaces with creasing, global illumination and HDRI light maps, a full-function parametric tree generator... I think you should try the demo to Carrara4. It's a 30-day fully functional (won't run plug-ins or render larger than 640-480). Carrara4 really isn't that different from 3 -- and up until July 14, the upgrade to 4 from a registered version of 2 or 3 is well under two hundred dollars US.