Moving site from 1.4.9.1 to 1.5.6.4

I've neem searching the board all they and i just can't seem to get the info straight.

Our webshop is running 1.4.9.1 and we want to switch to 1.5.6.4. Now we set up a test oc installation on a testserver. I tried to import the 1.4.9.1 backup into the new shop but clearly that's not working.

So what is the best way to go? Upgrade the current site to 1.5.6.4 with all risks involved or is there a way we can convert the backup so it does work on 1.5.6.4?

Hope someone can help because i'm really having trouble seeing the light here

You should be able to create a new database first. DO NOT use your existing store as the test to upgrade this far.

I'm guessing you've seen the scripts that are in the forum to get things converted?

DL