Changing post on page every couple of seconds

I’m building a theme in which there are 4 columns with different categories.

In those columns there should be only 1 post per category visible.

So far so good, got that working ??

Now I want that single post of each category to change every x seconds so all posts will be displayed one by one if someone looks long enough.

I saw a couple of plugins that will do the job but I want to build it myself.

I was thinking about putting the post ID’s in an array and then loop through that array, with a couple seconds pause each time, and put the output in the query_posts but then I have the problem that it will be changed on the server but won’t display on the page without a refresh.

Maybe I have to do it through Ajax calls but I’m hoping for a simpler solution.

Can anyone push me in the right direction? Not looking for the ready baked code, more for the right track of thought to tackle this problem ??

Thanks a lot in advance!