When you try windows update in vista computer, we get error an message with an error code : 0x80072EFD . This usually happens if the windows update is trying to access the Microsoft's windows update website through a proxy. To fix the issue, follow the instructions to connect directly to the microsoft website, instead through proxy.
Open command prompt with elevated privilages.
Type "netsh winhttp reset proxy" (without quotes) and hit Enter.
Reboot the computer and try windows update.