Thanks, Victoria Lee.

Its mainly the new cloud capabilities (i.e. the spectral and volumetric atmospheres) that I find attractive about v6. I got sick of rendering pictures where the sky only had wispy cirrus clouds.

I also noticed that (according to the Comparative chart) there is a 130% improvement in rendering - whatever that means. Sounds good though, as v5 often gave me a nasty message saying that it needed more memory than was available.  

Anyway, this is all attractive to me especially as I don't have a very gutsy computer (Pentium 3, 2.8GHz, 512 MB of RAM). Basically at the low end of requirements - but its worth mentioning that I also have Poser 7 which has similar requirements but I dont experience performance issues with it. 

regards,
Andrew