Windows 7 update is stuck at last check for updates on 25th June on this laptop belonging to a friend. Tried running the System Update Readiness Tool but the Hotfix for Windows KB947821 it wants to install first always fails, and you can't say no to this or it says process aborted by user.

Some other sites discuss copying files from another PC, which I don't have as I have a Mac. Also registry editing. Is there any way to fix this without doing either?

Win 7 SP1 isn't installed. Tried downloading it (as Win Update won't find it) but it won't run - the same 800737 error and advises downloading the SURT as above. The error again is Windows component store corrupt.

Win Update constantly wants to install 3 important updates, suspiciously all the same minute size of only 15kb - KB2676562, 2679255 and 2709715 from April, May and June 2012. These appear to install ok and go into the update history, but then show again and again as needing to be installed - clearly all related to the corrupt component store.