Check for System Update Readiness

Source

"CheckSUR" (Check for System Update Readiness) but many techies call it the Windows Vista Update Repair Tool!
CheckSUR will try to fix certain Windows Update installation failure causes.
For instance if Windows Vista Service Pack 1 won't install this is one way of fixing it and it's pretty cool...
Basically, all that is entailed is downloading the .MSU file and running it. During the installation it will run the checks and store the results at these locations:

%SYSTEMROOT%\Logs\CBS\CheckSUR.log %SYSTEMROOT%\Logs\CBS\CheckSUR.persist.log
So What Does This Tool Do?
During the life of your Windows Vista PC things can go wrong at times. For instance: missing files, invalid data, inconsistent data stores, invalid characters, XML parsing error's, incorrect parameters, out of date certificates, hardware fails and error's writing to files to name a few.

So this Windows Vista Update Repair Tool attempts to fix such errors.
If you have encountered a known issue that results in any of the following Windows Update errors:

0x80070002 0x8007000D 0x800F081F
0x80073712 0x800705B9
0x80070246 0x8007370D 0x8007370B 0x8007370A
0x80070057 0x800B0100
0x80092003 0x800B0101 0x8007371B
Then Windows Update or Automatic Update will offer the tool (KB947821) if such inconsistencies have been detected on the system.

The CheckSUR tool should run automatically after it has been installed from Windows Update and automatically fix any known issues.

Manually Download CheckSUR
Experience has shown that this tool is not always downloaded when it should be, or you have a persistent Vista update error that can not be resolved by any other means - then manually downloading/running this tool can sometimes help!

You can manually download the System Update Readiness Tool from the Microsoft Download Center. The following files are available for download:

Windows Vista
Download the Windows Vista package here
Windows Vista (x64-based systems ONLY)
Download the Windows Vista x64-based package here
This non-security update is applicable to:
Windows Vista Ultimate
Windows Vista Ultimate 64-bit Edition
Windows Vista Enterprise
Windows Vista Enterprise 64-bit Edition
Windows Vista Business
Windows Vista Business 64-bit Edition
Windows Vista Home Premium
Windows Vista Home Premium 64-bit Edition
Windows Vista Home Basic
Windows Vista Home Basic 64-bit Edition