Vocal Recording (for A Newbie) Options

[Dat Man Gaz]

Hi peeps

Im looking to use my Powerbook to record some vocals over tracks that have been pre-recorded. I have tried doing this by just importing the track from iTunes into GarageBand and then starting a new vocal track and just recording into the monitors built-in microphone, which obviously sounds poop.

I'd appreciate any tips on taking my set-up to the next level. Ideally I'm thinking along the lines of getting an external mic, but I don't know what else I might need or what type of mic to go for. The same goes for software - will I be able to continue using garage band or should I be using something else?

Gaz