Are these things all I need to record to my computer?

It all depends on what you are recording (drums guitar bass etc.) and how good of a sound you want. I record my bass riffs with just a cable that goes in the line out of my computer it's not incredible quality but it's not horrible.
 
I just want to record my guitar. I have microphone but I don't want to use it, because you can hear background noise and me strumming which I don't like.
 
I just want to record my guitar. I have microphone but I don't want to use it, because you can hear background noise and me strumming which I don't like.

If you're going for something acoustic, you'll need something with a piezo pickup run through some type of preamp (recommended) and then into your computer. If you're looking to record electric guitar, there's plenty of amp modeling items on the market that also have direct signal included.
 
What I'm trying to know is if the stuff I listed will help me connect my guitar straight into the computer.