High CPU Usage with Bluray

I was trying some blurays on a PC that I am going to use with my projector outdoors, and I decided to check the cpu usage.  I felt what I was seeing was pretty high.  The cpu is an E2180, and the video card is a 4550.  While playing Back to the Future, the usage was around 60 ~ 66%.  This was with TMT3 and TMT5.  I tried PDVD 10 and got around the same results, but I did see it hit 100% one time.  Later I tried Harry Potter and the Deathly Hallows and the average seemed to be around 35%.  So, not as high as BttF, but still high from what I'm used to seeing.  Not sure what version the drivers were at first, but I updated to 11.6, and it was the same.

I looked up a review of the 4550, and I found a test where a bluray was played and the usage on that system was around 11~18%.  Something seems to be going on, but not sure what.  BTW, this is on Windows 7 32-bit.  Any thoughts?