Recording music

I've read on the internet that recording music on a home computer is relatively easy... It says the key to good sound is having a good microphone.

I have a stock computer with stock sound cards, so would it be practical to record music on a computer by simply upgrading my microphone?

If anyone has tried this method I'd love to hear some tips or insight.... and I'm especially wondering if its worth buying a new microphone if what really counts is the sound card (which I don't plan on upgrading).

Thanks