I'm building an audio pc mainly as a source and I thought it might be a good idea to make it a Real Time Analyzer as well. I would also think this would be great for laptops, (used as a mobile thing to help others in their room). Maybe this is all old hat but it just came to me.

I know NOTHING about how to do this, only that I want to.

I thought others might be interested in the same thing so, I was hoping some people could list software, mic's, or tips on how to do set up a pc-based RTA.
Many thanks for advice!