If you use the upgrade script then yes they will all transfer. I have done several with virtually no problems.
**Make sure and Compact and Repair the 6.34 database prior to upgrading and do the same once the database is upgraded.
Also, once upgraded you will need to login with the default user/pass for a new forum. Then go into the Admin and use the Change Admin Username function to change it to your old user/pass from your v6.34 board. Resynch the topics and your old posts should relate back to your name.
Of course, I'm assuming this is Access powered and not SQL powered.