Yes, download the file mentioned, and after, in phpMyAdmin tool, or whatever mySQL command tool, execute the commands from !UPDATE_DB.sql file, renaming all tables by what you have in current database. For example, if you have "minibb_forums" table currently, then go through this file and search/replace "minibbtable_forums" to "minibb_forums" before execution.
After it, place the convdb.php
file into your forums directory, and run it, and choose "1.7 series".
That will be much easier and should upgrade the whole board... Afterall, you can create new tables for the forum, and specify them in options, if you want only users to be moved.
Also learn this solution of upgrade