Kingfisher, if you want to save some time while experimenting, you can open the BVH file in a text editor and lower the Frames value, which appears just after the hierarchy section. Then Poser will import only those frames, ignoring the remainder. I find this useful when testing large mocap files for compatibility. Life Forms Studio 3.5 does an adequate job of converting the .amc files. It was distributed on a DIGIT Magazine cover disc two years ago, if you can find a back issue.