Portfolio + Blog: multisite or plugin?

Question

I need to display both a portfolio and a blog on a website, and as a relative newcomer to WordPress, I was wondering what the most effective way is to do this: install a plugin, or create a multisite?

Essentially for the portfolio page I just need to display a thumbnail, category, and title, but when each entry is clicked, I need a full, blog-style post. Is there a plugin that will do this, or would a multisite (ie, running the Portfolio as a separate blog) be easier?