If I understand the question correctly. Moti and leifpettersen are asking how to import an old wordpress db into a new wordpress db. Since WordPress admin offers a super simple "Import" section with ability to import Textpattern, Dotclear, Movable Type, LiveJournal, Blogger, RSS, it would seem like a logical place to start. (BTW- Starkmann, I don't think you can "just point to your backed up database through your config file.")
In fact, your wordpress admin panel is a good place to start if you haven't created a backup db yet. To do that effortlessly you should install
WordPress database backup plugin
</a> This nifty plugin perform backs up your database automatically.
The second step, if you dig deeper in to Starkmann's link above you will find out that it is not the wordpress admin that can handle importing/restoring old dbs, but rather it is through your phpAdmin panel that this is done. http://codex.wordpress.org/Restoring_Your_Database_From_Backup
Also keep in mind your phpAdmin is also capable of backing up your db much like Skippy's plugin does, Skippy's simply simplifies the process.
P.s. What's with everyone misspelling WordPress? For a second I thought Wordpres was a splinter project!?