An audio interface is a standalone device designed solely for the purpose of handling high quality audio(prices vary). Internal soundcards pick up way too much interference inside the computer from the rest of the components, they are also fundamentally too small to handle a quality signal. You no doubt need an audio interface in any home studio. They aren't way over the top you could get a functional one around $200 or so.
And no it will not make your production better, but you sure will hear it better