Hi Chris,
I use 1280x1024 without any problems. It works well on my monitor.
I like the high resolutions because I can see more of the battlefield and still see the detail. This makes it easier to grasp the situation, which is important.
Resolution is a matter of preference but depends on how good your eyes are and also what kind of monitor you have. If you have a 21in monitor you can enjoy high res a lot more than someone with a small laptop screen.
I guess the main reason to buy the CDs is to support the game creators and developers, withouth whom there would be no game for us to enjoy. I would encorage other members to do the same - I think it is the moraly right thing to do.
Having tried both games against the AI and human players I intend to buy the CDs very shortly. This is, after all, the best strategy game I have played so the guys deserve my support.
From what I have heard in the forum so far, the filter facility seems more useful for WW2, so I guess I will buy that first.
I would caution that it is worth checking with our opponent if he uses the CD version before start of play. If you have the downloaded version you should agree no fire filter as part of the rules for fairness of play.
I also want to have a go at editing scenarios and campaigns, for which I think you need the full CD version.