Using both USB port and Line-In for Recording

Hi all, I do a podcast using Garageband. Up until now, I have had all my audio from my sound board/mixer go into my MacBook line-in outlet. I just ordered a USB condenser microphone which obviously plugs into the USB port. Will the Macbook recognize both audio signals simultaneously? In other words, when I record in Garageband, will the audio signals from both my line-in as well as my new USB microphone be recognized? When you go into the Audio/MIDI settings, the only options are line-in and built-in mic, which I have currently set to line-in. I'm not sure if USB is considered "line-in" or if it is completely separate from these two choices. Thanks!

No. One at a time. When you get the Mic you will find it will be picked up in the settings once plugged in (it may have driver software).

I have been doing some research on this since my original post and it appears there may be a way to do what I want. Apparently you can create an "aggregate device" using the Audio MIDI Setup within the Applications - Utilities Folder. Apparently here you can create a single channel with multiple microphone inputs (like two USBs or combination of USB and line-in audio). After doing this, you can go into Garageband and select the created "aggregate device" as a source.

I'm reliably informed by a regular Garageband user that you can assign a different audio input to each track you're recording to.
Robert's your mother's bit on the side.