Installing Parallels 4 seems to have been entirely unproblematic. It detected my Parallels 3 environment, backed it up, removed v3 and installed v4. I have about 4 back-ups lying around now, but it appears to have behaved very well. Time consuming given the number of times 12GB got copied. Nvivo is up and running maybe slightly faster than before (could hardly go slower!)
rWorld2 