Hey Tiffany,
Choosing audio recording gear is always confusing.
You've got a good setup now and it looks like the only thing you are missing is the audio interface. The M-Auido Fast Track Ultra is a fine way to get started. (I'm pretty that one has phantom power, but make sure it does before purchasing it.)
I say jump on that audio interface if it meets all of your needs. (If you aren't sure what your needs are, go through the beginner section here:
Home Recording Soundcard Wizard / Audio Interface Search Tool )
Check out this rebate:
Instant Rebates | Musician's Friend