Vista Update doesn´t work

Since I installed Vista Home Basic 6.0.6000 (Vista Retail) validated, I can´t
make updates.
I go to control panel/windows update. It searches for updates, than I get
the error message: 0x80072F78. So I searched this error number in Microsoft
website, and made all the changes, but it still doesn´t work. I disabled
Windows Firewall, disabled Avast, but I continue getting the same error
message.
I have also the same problem with Windows Defender. My definitions are
from07/2006. I put Defender searching for updates, or definitions, but
nothing happens.
So, I go to the security center, trying the updates, but they don´t work too.
Windows works fine, but without any updates.
Can someone help me?
thanks