On the 17th March 2008 Microsoft launched an important update for Windows Vista.

"CheckSUR" (Check for System Update Readiness) but a lot of techies call it the Windows Vista Update Repair Tool!

CheckSUR will try to solve certain Windows Update installation failure reasons.
For example if Windows Vista Service Pack 1 will not install this is one way of fixing it and it's cool...

Mainly, all that is entailed is downloading the .MSU file and running it. At the time of installation it will run the checks and save the results at these places:

%SYSTEMROOT%\Logs\CBS\CheckSUR.log
%SYSTEMROOT%\Logs\CBS\CheckSUR.persist.log


So What Does This Tool Do?
Throughout the life of your Windows Vista computer things can go wrong at times. For example: missing files, invalid data, incompatible data stores, invalid characters, XML parsing error's, incorrect parameters, outdated certificates, hardware fails and error's writing to files to name some.

So this Windows Vista Update Repair Tool tries to solve such errors.
If you have encountered known problems that result 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 variation has been detected on the machine.

The CheckSUR tool run automatically once it has been installed from Windows Update and automatically solves any known problems.