VO-BB - 20 YEARS OLD!

[slrsmith]

Hi - I'm Stephanie & brand new to VO-BB; thanks for having me! Also brand new to the VO biz and very green regarding tech stuff. I have a MacBook Pro (bought in '07) and am running iLife 08 with garageband. I bought the Blue Snowball mic but can't seem to get a decent sound with it after many, many attempts. My buddy (who wants to hire me for IVR/caller on hold gigs) says it sounds like I'm "underwater" -- not good! So, my next step was to try a new mic - if some of the experts out there could weigh in on the following questions, I'd love it:
1) Am I okay with garageband or do I need something more "pro" My gut is to start out this way and then spruce things up once I'm rolling...
2) What is a good mic for the Mac & Garageband? After searching this site, it sounds like maybe the AT2020 USB or the Samson CO3 or COIU USB?
3) Am I ok just using the USB mics or do I need to get more sophisticated right out of the gate?
3) Does anyone have a "standard" reco regarding garageband settings? My friend suggested treating recordings like music projects and using "Female Radio Noisy" The tutorial is not very helpful...

I'm contemplating ordering both of the above mics and just seeing what sounds best...also am going for a 1-to-1 at the Mac store next week. to see what they might say. THANKS IN ADVANCE for taking the time to reply!