nForce 2 APU - Abit NF7-S rev1.2
Logitech Z-640's
And for headphones, I have a pair of
these excellent things, which I bought when they were on sale for $4.95.

I've also got a
Wowthing - no, I don't know why they called it that.
But it serves as headphone volume control and sound enhancement, as the z-640's lack volume control for the headphone jack. The sound enhancement is great too - the bass can be turned up so much that I get a headache after watching the battle sequences of Deep Space 9's "Sacrifice of Angels" episode (Dominion vs Starfleet). Those headphones are quite capable.