Blu-ray stuttering HTPC

[imprex311]

I know this has been covered a lot, but I too have a stuttering issues on my blu-ray HTPC. I think I have a new angle that might help fix it, or at least better understand it.

First here are my system specs:
AMD Athlon 64 X2 4400 - brisbane
Abit M2N-HD Motherboard
2GB Gskill RAM DDR2-800
Windows XP Pro (updates disabled, its an HTPC, I dont like windows making it restart all the time, I last updated it about 3 months ago)
ASUS Nvidia 8500GT 256MB
DVI to HDMI cable to Sharp 37in 1080p TV

Here is the problem, I am able to play most blu-ray discs at 1080p with little or no issue. I recently had trouble with Resident Evil Extinction. The disc is basically unplayable at 1080p and marginally better at 720p. What I found is that when playing most discs my CPU usage is 40-50%, but when played Resident Evil, the usage was around 90-100% hence the stuttering.

I have found that Resident Evil Extinction is profile 1.1 and I think that is what making the difference. So my question is this: Does the video card handle the profile data, or is it purely the CPU that handles it?

I assume the CPU handles that data. I admit that I could update video card, off load all of the video data and the CPU can be completely freed up to handle the profile. Does anyone have any information regarding CPU usage for different profiles?

Im open to any ideas you've got.

Thanks in advance