Upgraded to mysql 5 and PHP5, now weird characters in blog posts

Check this out:
https://validator.w3.org/check?uri=http%3A%2F%2Fblog.dmb.hey.nu%2Farchive%2F2006%2F06%2F05%2Fopen-source-the-fear-of-closed-protocols%2F

Why would that happen? How do I fix that? I think its related to the upgrading of mysql 4 to 5.

Whats weird is if you do mac encoding it seems to work(https://validator.w3.org/check?uri=http%3A%2F%2Fblog.dmb.hey.nu%2Farchive%2F2006%2F06%2F05%2Fopen-source-the-fear-of-closed-protocols%2F&charset=macintosh&doctype=Inline), and when i was checking website at school on a mac, you couldn’t see it.

Go to:
admin -> options -> reading

Box at bottom for encoding should be UTF-8

Validator says it’s not.

It is allready at UTF-8 in that box.