You're welcome Irene! If you've been "making movies and idvds" you are far from "computer illiterate" 🙂
LCD screens typically show the characteristics you mention, ie, change in brightness/viewability when viewed from different angles - unlike the "old" CRT screens (which my iMac has). You're almost putting me off upgrading to a new iMac G5 (joke). The problem shouldn't be as severe as you are describing though.
So, I went back to your initial post and noticed that you are "importing analog movies through a dazzle hollywood dv-bridge". I had forgotten this in all the to-ing and fro-ing. This may be part of the problem re your dark scenes - they shouldn't be as bad as you've been describing (the iMovie preview screen is not that bad).
It might be worth you doing a search in this forum on the "Dazzle" - I vaguely recall others having problems with analogue/dv converters, but the problems may have been different to yours. Further, you may wish to re-post under a topic heading which includes the name of the converter, eg, "Dark imports using Dazzle Hollywood DV-Bridge" or similar. This might catch the attention of Dazzle users who may have experienced a similar problem. It might be worth including a link to this thread - control click on your name in your original post (or the blue numbers under a posting), select copy link and paste the link in your new posting.
I can't offer any help on the Dazzle, as I import analogue footage (rarely) through my Sony DCR-TRV20E mini DV camcorder using the pass-through mode.
Your idea to "burn a trial project" sounds good. It's the only way you will be able to check the final product. If it's nowhere near your expectations, I would tend to think the converter is the problem.
John