What NLE software (other than premiere) will allow me to set timeline
markers on audio and video clips so I can synchronize the video clips
with the audio/background music?

I know how to do this with Premiere but unfortunately, even after
locking each clip and the audio track, the clips and music do not stay
synchronized.  I can't figure out why it gets out of synch and the
project is due for Christmas! (Pressure's on)

I really like Pinnacle Studio, but there doesn't seem to be anyway to
do this other than trial and error.  "Edition" seems to have a
shallower learning curve than Premiere (in my case).

I want the software to have these features:
1. Ability to mark clips (audio and video)
2. Dragging clips on the timeline by markers should snap to other
markers (ala Premiere)
3. Background/Smart Rendering or P4 optimized rendering
4. Accurate scene detection from DV. Preferably to individual files
instead of just .scn data files and one big .avi file.

Nice to have:
Default transition added when clip added to storyboard/timeline
Still images should default to maintain aspect ratio

Functional try-out version must be available. Can't waste more money.

http://www.puremotion.com/downloads/index.htm

try edit studio, i have been using version two and find it very
professional - version 3 seems more domestic (wizard style) but i
don't think you need to use them and still has many power features

Thanks, this program has a lot of potential.  Easy to learn.  Lots of features.

-Jack