I would love to allow people to add articles to my site.
But I don't want them to login in, since that will stop them submitting articles.

Once an article is submitted, it gets into 'review' modus.
I need to review to and change it to 'publish' to get it on the site.

is this possible with this system?

Not possible without having an account I'm afraid.

You can create access levels that mean when users post a new article it doesn't get shown until it gets approved by a mod or admin, but in order to do this the user must have an account.

why dont u add a form that would send the 'article/news' to your email directly. You can then post it later whenever you want. sounds easy to me.