John's answer is really good if you want to use the computer exclusively to record your guitar. I was a professional musician for over 20 years and my preference was and still is to use a independant multi track recorder to record live instruments. The reason, is that you have a direct plug in for the instrument built in pre amp for guitar, bass and microphone, and you can control eq.
The small portable 2 track machines run around $100 US, and they are made by Tascam, Zoom, Boss and many others. The key is to get one that exports the files as .wav and or .mp3.
I like this approach because I record the riff and just drag it in to Music Maker.