Hang on....Exactly WHAT did the Windows Security Center say was not enabled when you checked it? You DO have an anti-virus program on there, you can see the entries in the HJT logs so it shouldn't be saying that
"Your computer is not protected because anti virus software is not installed. Click on the balloon to fix this problem"
Do you have a firewall on the computer? Was that the security center said, that there was no firewall?