Applications :: Learning Guitar On GarageBand?

I admit I have never really touched a real guitar in my life (obviously a Rock Band guitar does not count). But since I just got my new 27" iMac, I came to the realization that learning guitar with GarageBand might actually be pretty interesting.

So, what is the minimum buying requirements in order to start learning guitar when you are starting with nothing (other than GarageBand itself, of course).

Here is what I think I need at a minimum, but I want to make sure:
Acoustic Electric OR Electric guitar. A regular acoustic guitar won't work because it does not have a line output (is that correct?).

I have seen some acoustic electric guitars on eBay for less than $100. What do I need to make sure the Guitar comes with before buying? [By the way, I have my eye on one acoustic electric guitar that comes with an Active Pickup ... is active pickup necessary?]
1/4" to 1/8" adapater

Here are some extras that might be nice for better tone, but are not required:
USB or Firewire Audio Interface. I think I have seen I can get one of these for $50-$100
A microphone to connect to the audio interface
An amplifier

I was thinking of starting with the minimum requirements (assuming what I listed is the minimum) and if I decide I enjoy this, go for the extras I listed.

Do I have this all correct?