What do you want to do that you can't do in Garage Band? I'm not trying to be sarcastic. But you haven't given us much to go on other than the fact that you want to record rap vocals and have an inexpensive USB mic. If you have Garage Band (which I assume is already on the Macbook pro) I'd suggest you use it until you run into it's limitations. A lot of people have made very cool stuff with simple programs like this.

So I am unclear here. You have a MacBook Pro and you have an HP laptop. The MacBook Pro must have set you back at least $1500? Garage Band is a fine program to start with. You went out and spent a whopping $80 for a microphone that will generally do a pretty crappy job of recording rap. How to make it good? Large foam pop filter and a nylon stocking lollipop, both. Once you have learned and mastered your Garage Band software, you may find no need to change. You certainly paid for more than just a laptop computer. This is all you need to make your first $1 million with. After you make your first million, you might want to buy a second one of those Behringer microphones?

Hey yo yo hey
Mx. Remy Ann David