I had the same symptoms described throughout the post. I have it fixed the problem on my machine and this is what I did:
Uninstalled everything affiliated with Apple software:
iTunes 10.4
Apple AppSupport
Apple Mobile Device Support
AppleSoftware Update
Bonjour
QuickTime
Safari
Ran a program (Advanced SystemCare 4) to look for, identifyand delete any files not deleted with the original removal, in particular toclean the registry for any remnants of Apple software. There are lots of registry cleaningapplications to choose from.
www.iobit.com/advancedsystemcareper.html
(I paid for the fullfeature application, the free version may work, but doubtful)
Ran a thorough defrag on the entire drive.
Re-booted the system.
Downloaded and reinstalled the iTunes 10.4 application.
Everything worked fine after the above referenced process,including resolving the system resource spikes on the CPU and Drive. I did not install Safari.
I’m using an HP laptop (approx 4 yrs old) with XP and SP2and SP3 updates with an AMD processor. Hope this helps or at least colaborats some of the other posts. Good Luck.