Guitar input to macbook?

So I have always been interested in making my own music, but have never had the money, however, I graduate in a couple of days and I will have the money to buy some new gear. My question is this, I am getting a Macbook with LogicExpress(and will probably get Adobe Audition soon) and I am getting a small keyboard interface thing(not sure of the exact name of the device, but I know it's application) but I am not sure what to get. I have the keyboard device picked out, but i do not know how to get my guitar plugged into the computer. I know of some ways, but I want very good quality, which does not come with the methods I currently know of. So what would be the best method of inputing it? are there some of the MIDI Keyboard things that have inputs for other things that will provide good quality? should i find a certain kind of mixer for it? I am a very fast learner, and, despite my lack of terminology, I know quite a bit about how things work, so don't assume I'm just some dumby looking to get into this. i just need to know if i can find something that does it all, or if I should get two seperate devices. I am not looking to spend a boatload on all of it, but i am also not looking for the cheapest thing out there that will do a halfass job. any product suggestions, or anything like that would be greatly appreciated.