So, I'm looking at a brand new Fedora Core 9 installation, just to try things out. Lots of problems, but one thing at a time I suppose. My first task, I decided, would be to try Amarok which comes installed with FC9.

I open Amarok, get some MP3s off my external HD, and load them up. I click play.

The xine-engine claims it cannot play MP3 files.
You may want to choose a different engine from the Configure Dialog, or examine the installation of the multimedia-framework that the current engine uses.
You may find useful information in the FAQ section of the Amarok HandBook.
There's a Helix engine available which I choose, but I get the same error (xine replaced by Helix). I open up the Amarok HandBook and I find out that these are required for Amarok to run:

Chapter*8.*Requirements
Amarok requires the installation of some software packages. The required packages are listed below along with several other packages to enhance your Amarok experience.

Required:
KDELIBS 3.3
TagLib 1.4
How can I find out if I have them installed or not? Where else can I look for errors/troubleshooting? What about sound drivers, I've got an onboard sound card, how can I check if it's functioning properly or not?