MySQL install or upgrade

Hi Chris,
It's me again, I've got a problem with my old host mysql.

I was using MySQLv.4.0.2.6 and I want to change it to MySQLv.4.1.2.0 instead. Due to the security issue. Anyway I've dumped my several of my databases and try to import them to new database. However, the new sql server gave me a lot of errors while importing tables and data.
Now after I've finished import my database, I've change back to my backup board which currently connected to the new database. The webboard looks fine but the posts and all the others data are messed up. I'm using Thai character(tis620) but now it appears as ???????? instead.