Upgrading MySql from 4 to 5 on 1and1

WordPress 2.9 is out today, and we’re trying to upgrade all our blogs to it.

These sites were created with MySql 4 databases, and the latest WordPress requires MySql 5. How to upgrade?

So far, we’ve tried dumping/exporting the old database and importing to a new MySql 5 database, but certain characters like curly quotes and Greek letters are broken.

Any ideas on dealing with these character encoding issues?