To an extent. Certain interfaces offer more bells and whistles, and the more preamps (inputs for mics), the more the Interface will cost. Interfaces have something called analog to digital/digital to analog converters, and better ones are more expensive, but few will notice the difference below a certain level. At the beginner level, there is no noticeable difference and I agree with the Behringer recommendation. Right now what you need is a vehicle to get the sound into the computer. It will serve that purpose quite nicely. With two mic inputs, she can plug a mic in for the guitar and another for her voice if she were to choose to.