Firefox accepts the IE favorites if you set up the IE first and add the favorites as John suggested. Install Firefox after that and let it import all of the IE favorites.
My kids use Firefox as their default browser and have had no complaints. I go back and forth between several of them, and the main reason I use IE most often is because I haven't kept up with the favorites in Firefox. I'll have to reinstall it myself one day soon and let it pick up all of those favorites.