Finder Slideshow - turning Random off

When I use the Slideshow facility built into Finder, my pix come up in a random order, regardless of how they're sorted in Finder.

I've had a look around and have found a way to change the timing of the Slideshow, by editing its config files in the Library, but can't see an option to turn Random off. Can anybody tell me how to do this, without using a different slideshow viewer such as iPhoto?

Thanks.