If you use T-Bird and Lightning as I do, look into Google sync for contacts and calendar. I don't use the contact sync as most of mine are static, but I have found the calendar sync works very well to keep the Lightning on the Macs, Outlook 2003/2007 on the PCs and the BB and iPhone calendars in sync. You will get an occasional dupe, but I have not found that to be a big issue. Use Google's search feature to find out more.
You are correct about having to use DM 4.2 for Outlook 2000. DM 4.3 and above will only work woth Outlook 2003/2007. Not sure what the plan is for 2010 though.
Of course email doesn't sync if you are on BIS.