Thank you for your input, Ivan. The job is done!
Moved my forum to a new server and made the upgrade from 2.0 RC2a to 2.0 Final.
I had to import the database through SSH because it was about 39 megabytes and phpMyAdmin cannot import files > 2 Mb. I also had to change the "ENGINE=MyISAM CHARSET=latin1 AUTO INCREMENT=..." lines in the dump file into "TYPE=MyISAM AUTO INCREMENT=..." in order to get the import done. Finally I had to remove some lines from the !UPDATE_DB.sql file because, apparently, they had already been executed (found this strange).
At first sight everything seems to be fine, except for 2 things:
1) When I want to edit messages that have been posted prior to the upgrade, I also get the html-codes in the message form, mostly <br>, <b>, <i> of course.
I don't have this problem with new messages I post (under 2.0 Final). When I take a look into the MySQL database, I see <br /> is placed in the new messages, instead of <br>, <b> becomes <strong>. <i> becomes <em>. So I assume I can correct the problem by changing all <br>, <b> and <i> tags into <br />, <strong> and <em> in my dump file?
2) The server that hosts my forum is based in the US. But all visitors to my forum live in Belgium and Holland in Europe. We are 9 hours ahead of the US. All time stamps under 2.0 RC2a are correctly showed under 2.0 Final. But now, after the upgrade, when I post new messages, the timezone for those new messages is, of course, US. I asked the webhosting provider if they could change the timezone, but they say it's not possible.
Of course, this is a major issue. So my question is if there's a possibility (modifying the forum code somewhere) that all new messages get the US time stamp + 9 hours ?