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!"
I understand the cleanliness of the pictured solution, but for those unwilling to crack open the box (esp. those leasing the machine), why not do the same thing, but mount the fan on top of the box. I'm sure the vent holes could be used to crudely secure a fan and keep it from vibrating and moving about. Just a thought.