“A critical update is needed. To continue this installation, you need to install Windows Update Agent 5.8.02469 or later..”

Some people may have encountered this message during installation of Windows Live Messenger downloaded from websites other than that of MSN’s. Like what happened to me, I download my softwares from FileHippo and when i tried to install Windows Live Messenger, that message showed up.
Upon doing some Google search, i realized that this will really happen especially if your OS is not being updated with Windows Updates. Since i usually have my Windows Update turned off, then this scenario is expected.
So how can we upgrade to or install the latest version of Windows Live Messenger? I’ve listed two ways i found:
1. The quickest and easiest way is to download Windows Live Messenger from the MSN website (This is I did and it worked!hehehe ). The installer there already comes with the installation agent Windows is looking for.
2. Turn on Windows Automatic Updates and download everything needed up to the latest patch. That would include the installation agent already after which you can already install Windows Live Messenger using an installer from other sources.
3. This is a step that would allow you to download everything up to latest patch as a package without turning on Windows Automatic Updates.
a) Download http://update.microsoft.com/redist/wuredist.cab from microsoft site.
b) Open the cabinet file and you will find an xml manifest wuredist.xml. Open it using notepad or any text editor.
c) Check the DownloadUrl attribute for your OS architecture (x86, x64, ia64) for the download url from where you can get the download file. To know you OS architecture, right click on My Computer on your Desktop and choose Properties. In the General tab, under the Computer section, you’ll see it beside the Motherboard name. (e.g. AMD Athlon(tm) 64 X2 Dual Core Processor 4000+)
So for the x64 platform, the download url would be: http://download.windowsupdate.com/WindowsUpdate/redist/standalone/7.0.6000.381/WindowsUpdateAgent30-x64.exe
d) Download the file and install.