I get the same error when attempting to download Vista SP1 via Windows Update and when installing the standalone version of SP1 (I get "internal error.." and the error code 800703EE). The article http://support.microsoft.com/kb/947366 might be of assistance to you, "wilfsta", but nothing worked for me on it...
80073712 - ERROR_SXS_COMPONENT_STORE_CORRUPT.
> Windows Update file corruption.
> Delete the file pending.xml under C:\windows\winsxs
> Reinstall the Windows Update Agent
> Windows, x86-based systems
> Windows, x64-based systems
- Proposed as answer by Steven GJ Thursday, July 15, 2010 11:18 AM