I have a C3-700 which is running fanless. It's an ezra core. I think I've read people going to 900 fanless. I have it in a MicroATX, a tight fit case and temps ran cool. I don't think you'll have any problems there. Just get a nice big heatsink (siliconacoustics carries one). In addition, you could go the extra mile and put some Artic Silver but I just used regular "plain jane" thermal compound.
The cuda Iv's are by nature hot. I have one in another MATX running 24/7 and it's ok, but it is warmer than what I'm used to. If you concerned, you could get a Panny 1A or Papst fan to cool it a little. I've read (probably on usenet) but can't personally attest to its veracity, that a Maxtor @ 5400 is just as quiet. Don't know 'bout that as anything else out there without a fluid bearing motor sounds like a whining house wife to me.
Hopefully someone else can chime in and share some insight.
Anyway, I hope this helps you a little.