update Kb937287 error code 800b0100

Can't install this update. Contacted Microsoft, various suggestions, none of
which worked. Have been told I need to do program recovery and wondered if
anyone knows how to save installed software so that I can reload it in one go
afterwards instead of having to reinstall one by one. I have Windows Vista
Home Premium pre-installedon computer when purchased. Can I use an external
hard drive to save programs onto and then re-instal? All my files are backed
up so they shouldn't be a problem, but do e-mails and e-mail addresses get
saved onto disc when you back up files, or do I need to save them separately?
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thanx