I'm no expert but I have been having the "Readyboot" errors too. Here's what I followed to resolve:

Session stopped due to the following error: 0xC0000188

Thanks for posting this as I had the exact same error and at the exact same point during the install. I disabled my antivirus software (Avast free edition) and the update proceeded successfully. (I...

Works great for me. I had the intentions of following up with a clean install but the upgrade is performing just fine for me.

Nothing on my Win 7 Ultimate 64 bit either