I getting a little more on my upgrading think.
Now I can run the "threads_import.php" and get errors...

better then before when I could not run at all.
I didn't have the folders /libs and /styles on my OLD installation. I just copy those files from the new install (version 7).
Also, there is something funny with the 'language' path.
My forum had a language different then English as a Primary.
I change it back to English, but continue with the very same error.
Please, see the errors:
Warning: set_style(/styles/.php): failed to open stream: No such file or directory in /usr/local/etc/httpd/htdocs/imigrar/forum/libs/ubbthreads.inc.php on line 368
Warning: set_style(/styles/.php): failed to open stream: No such file or directory in /usr/local/etc/httpd/htdocs/imigrar/forum/libs/ubbthreads.inc.php on line 368
Warning: set_style(): Failed opening '/styles/.php' for inclusion (include_path='.:../PEAR-1.1') in /usr/local/etc/httpd/htdocs/imigrar/forum/libs/ubbthreads.inc.php on line 368
Warning: not_right_bare(languages//generic.php): failed to open stream: No such file or directory in /usr/local/etc/httpd/htdocs/imigrar/forum/libs/ubbthreads.inc.php on line 799
Warning: not_right_bare(languages//generic.php): failed to open stream: No such file or directory in /usr/local/etc/httpd/htdocs/imigrar/forum/libs/ubbthreads.inc.php on line 799
Warning: not_right_bare(): Failed opening 'languages//generic.php' for inclusion (include_path='.:../PEAR-1.1') in /usr/local/etc/httpd/htdocs/imigrar/forum/libs/ubbthreads.inc.php on line 799