Well, like I said, you really HAVE to go to 7.5.5. The import script won't work with 7.0.2.
What you should do is grab 7.5.5 and install it into a new directory, something other than your 6.5.5 directory. Then bring up the importers/threads_import.php, fill in the info it asks for and then let us know if you get any specific errors.
okay...i unzipped 7.5.5 into a new directory (/ubbthreads-7-5-5)
ran the install utility, it found my databases and was "creating the tables" (url: http://xxx.../ubbthreads-7-5-5/install/createtable.php
then i got this:
Warning: main(libs/phpmailer/class.phpmailer.php) [function.main]: failed to open stream: No such file or directory in /home/web/public_html/owners.only/ubbthreads-7-5-5/install/createtable.php on line 37
Fatal error: main() [function.require]: Failed opening required 'libs/phpmailer/class.phpmailer.php' (include_path='/usr/local/php/includes:/usr/local/lib/php:/usr/share/pear') in /home/web/public_html/owners.only/ubbthreads-7-5-5/install/createtable.php on line 37