Let the hive mind of Engadget get that for you.
"I've found myself using my PC for a lot of conversations lately, and I'm also considering recording a podcast to share with anyone who will listen. There are tons of USB headset / microphones out there, and I'm hoping someone has some solid recommendations based on experience. I'll consider both headsets and standalone mics, by the way, but I'd like to keep the bill under $100 if possible. Help!"
For folks with pre-HDMI AVRs: consider a blu-ray deck with internal decoding (e.g. Panny BD50) and multi-channel analog outputs. Assuming you have such inputs (most higher-end AVRs from the DVD era have 5.1 analog in at least), you can avoid changing anything. Very little besides blu-ray needs anything past DD or base DTS over optical.
HDMI/HDCP is more to be avoided that "upgraded" to.