Legacy mailbox issues after move to exchange 2007

I am experiencing a couple of problems with mail accounts after moving the mailboxes from exch 2K to exch 2007. One of them is out of office replys, user can edit and save the new out of office response but it sends an old one, moving the mailbox back to 2K solved this problem. The other is read receipts, read receipts continue to function after turning them off. These clients are still using outlook 2K.

Anyone experience this or have any advice? I am planning an upgrade to Outlook 2003 byt the end of the year but I would like to fix this without having to do that now if that in fact is the issue.

Thanks