Boot into XP. Open Mozilla browser. I don't use it so do not know exactly where to go, but there will be somewhere under bookmarks or favorites an option to Import. Hit it and it should ask you to specifiy the source - navigate to your favorites folder in Win98 and that should do it.
Similar process for email I would hope. An import facility on either the file or tools menu.
To be sure of the precise methoid I would suggest you go to the support pages at the Mozilla site.