Cut W7 down to bare essentials for WMC only

I have two HTPC's very similar builds run W7 Home Prem. 32bit and want to strip the OS down to only what WMC needs to run. They are running on P4 3.2g Prescott processors and I KNOW this is enough horse power to perform as great HTPC's. They both work very well watching and recording full HD programming from my Silicon Dust home run Prime except when Windows wants to do its house keeping, then frames are dropped or it freezes for a half second or less. My question is, is it possible to strip windows down to only what WMC needs to run? I would like a custom build of WinCE with WMC for the P4 and my current hardware but I'm sure thats asking to much or have a hefty price.

Well, what is Windows doing when the machine is sitting idle and then your CPU usage spikes and it bangs away at the hard drive, mind you theses machines have clean installs and have never been used on the internet except for updating themselves through Microsoft Windows Auto Update, and all drivers were installed from OEM CD's, so I don't suspect a virus, trojan or malware.
Thank you for your reply.

You don't have Chrome installed do you?

I setup a PC using that processor and Google Chrome caused the same symptoms.
Uninstalling Chrome fixed that, Chrome does use a lot or resources.
Use a SATA not IDE drive, if you have SATA ports.
I have a larger better quality IDE drive i am using, 320gb Maxtor, some of the smaller WD !DE like 40 to 80GB, they caused me same glitchy troubles. I also boosted the board speed as much as it can tolerate.

ALso get rid of antivirus. Just keep a backup of the drive, a clone. Then you can restore drive to drive in a few minutes if you got infected. Your not going to get a virus, if you dont browse the net, or stick in unknown usb drives.

My problem was once a glitchy blocky smearing of the picture started appearing in the display for HDTV 1080P, it would not stop till I closed WMC and reopened, then it would work ok for a random amount of time.

The CPU and mother board will always be underpowered, WMC and windows just are almost too much for HDTV 1080P to work well with them.