I was going to come here and ask the same question a few days ago. What I tried was exporting my bookmarks on one computer and I imported the bookmarks.htm file on the other. I wound up with something very strange on my laptop (the 2nd computer). Each bookmark was there in duplicate. Maybe I'd done it before and I guess that would explain the duplication.
I do like the way IE manages bookmarks, by having a separate directory for each folder. To me it seems easier to manage things than the HTML file that Firefox uses. For one thing, managing and organizing bookmarks has seemed to me so far to be a lot easier in IE. I'm relatively new to Firefox, but that's what I see so far.