Better Sound Options

I am an audiophile, I love music very much. My PC has a built-in sounds on-board and a standard multimedia speakers. The sound is not too good in quality like of those from my friend’s sony disc player. I want a better one, so I considered to upgrade.

My question is, which component do I have to upgrade? sound card or speakers? Which is the best option. Hope you can help me.

Thanks in advance!