I don't know if this will work for everyone. I'm in the same position where I have one of my cores maxed out by the AppleMobileDeviceService. I did have success in the past by removing the third party layered service provider (LSP) but, of course, that's not the issue this time.
What I've done recently which works like a charm is to restart the AppleMobileDeviceService. That's it. It gives me a warning that it may not be restarting under the same ID it was running under before (my ID is an administrator on my machine so I wasn't too worried) and I have no issues. My iPod and iPad both sync just fine.
I need to do this only once after iTunes is started and I'm fine until I restart the app again. Of course it would be handy if iTunes wasn't bloating up to the point where I need to restart it every few days or it runs out of memory but that's a topic for another forum thread...
Further details: I use Microsoft's "Process Explorer" as a replacement for task management so I have an option to restart the service directly from that tool. I presume you could do exactly the same way from the Services app in Windows.
My machine is running Windows 7 64-bit and I'm running iTunes 10.7.0.21
