Requirements for a HTPC

My replacement powersupply, a Shuttle PC55 450W, sounds like a helicopter taking off.  It's a least 20db higher than the stock 350W.

It's getting long in the tooth so now I'm thinking about a new HTPC.  My must-have features:

• quiet, I don't mind a small amount of noise.
• 1080p playback of h264.
• small, shuttle size would be acceptable.
  
• good video graphics, either with ION or a PCI Express slot.  I'd like to use the GPU for flash acceleration.
  

I'm considering something extremely small, something like ASUS's EEE Box 1501, http://www.pcper.com/comments.php?nid=8027

[UPDATE] The pc55 isn't as noisy as I thought.  I had a cable rubbing against the fan, ugh.