The first thing to do will be to get the SQL 6.5 databases into SQL 7 or higher. This is done by restoring the SQL 6.5 database to another server with SQL 6.5 on it, then installing SQL 2000 on the machine. SQL 2000 will include a SQL 6.5 upgrade system which will help you do the upgrade. I recommend doing this on a seperate machine in case something goes wrong.
After the databases are all in SQL 7 or above, you can take a full backup of them, and simply restore them to a SQL 2005 server.