Windows Update see no SP1 and can't install the full upgrader file in my 64-bit W7 HPE machine.

Hello.

My 2.2 years old, updated 64-bit W7 HPE's Windows Update sees no SP1 and
can't install it with the local full 903 MB upgrader file from my local
HDD I downloaded. The local upgrader says "Install Windows Service Pack:
One or more system components that the service pack requires are
missing..." I went to its link to
http://windows.microsoft.com/en-US/...ts-missing
... It says I need to reinstall. Do I really have to reinstall it? I
don't have the OS DVD since it came with this 2.2 years old Dell Studios
XPS 8000 office desktop PC? :(

Windows Event Logs (System) showed "Service Pack installation failed
with error code 0x800f0a13." Are there any other logs to show what could
be the problem?

Thank you in advance. :)
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