You're not alone. I'm running a old Toshiba Satellite L305-S5921 that came with Vista. At first chance I entered the Windows 8 beta program and took advantage of the $36 upgrade to Windows 8 pro...

I've been able to stop the process by hiding the appropriate updates, and using 'disk cleanup' > 'Clean up Systems Files' to rid myself the temptation to try another failed update.
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