Acoustic guitar into iMovie, do I need a preamp? Options

[strummer]

I want to add some simple acoustic guitar tracks to an iMovie video.  Can I use a small diaphragm condenser mic (like the Rode NT3) with a 9 volt battery, run it through iMic, and record directly into iMovie, just as if I were adding a voiceover?  Or do I definitely need a preamp?  How about doing that same thing with a pickup (like the AKG C411)?  Any alternative suggestions would certainly be appreciated.