Same post and post categories for all created blogs!

Hi.
I want to have my posts (sorted by categories) created by default when a multisite user registers a new blog..
I have 11 posts created sorted in 4 post categories on the main blog…now I want to make these as default, so when a user registers a new blog he will have the same posts and post categories and of course the content of the posts too on his blog.
I know it is possible I just can’t figure it out now…and thought I’ll ask for your help…

Thanks in advance,