Windows can't update

My Computer: HP Pavilion p7-1020 running Windows 7 SP1 Home Premium 64 bit with all updates through 3-1-14. Also running AVG Internet Security 2013 with all current updates.

I have Update set to let me know when updates are available. I then download and install, typically as soon as I get the notification.

Problem (starting around 3-11-14): When I run Windows Update I get:
Error Message: "Windows could not search for new updates"
Error Code: 80070002

What I've tried:
Disabled update service, rebooted, renamed C:\Windows\SoftwareDistribution to ...SoftwareDistribution.old, restarted update service and rebooted.
MS Fixits.exe: MicrosoftFixit.wu.RNP.15031948315891424.1.1.Run.exe
MicrosoftFixit.wu.LB.2731948003758378.10.1.Run.exe
MS Update Standalone Package: Windows6.1-KB947821-v32-x64.msu
MS Malicious Software Removal Tool: Windows-KB890830-x64-V5.10.exe
MS Troubleshooting Pack Cabinet: WindowsUpdateDiagnostic.diagcab
Chatted online with MS "expert" who suggested I had a rootkit infection and should reinstall Windows.
Posted in Malware Removal section of this forum ("Windows can't update") and followed Kestrel13!'s instructions to no avail so I was directed here.

 

I do have TrustedInstaller.exe.

Tried sfc /scannow but "Windows resource protection could not perform the requested operation."

Can't try the In-Place Upgrade because I don't have a Windows DVD. I was going to download the ISO for Windows but MSFT has taken it off their site. Not sure it would have worked anyway as I only have the HP product key.

The original HP HD failed. Had a local shop replace it and "copy" everything onto the new drive. Unfortunately, they're no longer in business, they didn't copy the HP partition onto the new HD and the product key they used to install Windows has been blocked by MSFT.

I do have the Recovery DVDs I made when the computer was new but not sure if they'll work without that HP partition.

I see digisoftstore.com offers a Windows 7 download with product key for $69. Do you know if this is legit?

 

You can get a RTM version HERE which should work with the HP key on the CoA sticker, but you would have to install SP1 and all succeeding updates. Save all your stuff first of course and I would advise imaging the system as it is now in case this fails..

 

Thanks Earthling.

Tried that ISO and it worked but it won't do an In-Place Upgrade because the installed version is later (SP1) than the ISO. I really want to avoid a complete reinstall if at all possible.

Think I'll wait awhile and see if MSFT puts the SP1 ISO back online.