Plugging Guitar into Macbook Pro 13'' - Audio Interfaces

Alright, so I've done a fair bit of research but there just seems to be so much to read out there that I figure it may simply be easier to post this here and see what kind of answers I get. Anyway, I want to plug my guitar and record some stuff on my macbook pro (13-inch, core-2 duo) and i'm running Snow Leopard. I'm a pretty seasoned guitar player, but I'm not looking to do the heaviest and most intense recording here, I simply want to be able to decently record some stuff onto my mac. I know with my macbook it has a dual audio input/output jack, but I don't exactly want to plug in through the input though because I want the output going into some speakers, and using the input jack really isn't the greatest (especially when I'm plugging into just an electric guitar). So my options appear to be using an audio interface, but first question is whether or not I should be looking at USB or Fireware connections. Secondly, I read some stuff about the Apogee Jam thing (which is usb) and is reasonably priced, along with M-Audio Fast Track (also usb) and is a little higher priced. Basically I'm looking for something that is reasonably priced (as I'm not professionally recording here) around the $100 range, but produces a pretty solid sound quality, and works fairly well...the best bang for the buck, if you will.

Any help would be greatly appreciated. P.S. I also have an amp that I could use that has a headphone jack which I can plug the guitar into the amp, and the amp into the computer (but again, it seems as though plugging into the input really is not the greatest call).

Thanks very much!