Check Marc Peter's post for guides to the main software vendors. I know that ULead provide trial download. Some of the others may too.

http://www.videoeditingforums.co.uk/viewtopic.php?t=548

I don't know of this will resolve your sound problem. Check your card settings and remember to match colours when linking your camea to your card. Yellow to Yellow (Video) Red to red and White to White.

Good luck!