As my Windows XP installation had become too slow and sluggish, I backed up all data and reinstalled Windows XP. I normally use Windows Live Writer for posting to the blogs, therefore I downloaded installer from Windows Live Writer website. However when I tried to install I was not able to install Windows Live Writer, as I was getting the message, a critical update agent 5.8.02469 or later is required for installation. To overcome this difficulty I searched the net for critical update agent 5.8.02469 or later but soon was disappointed to find no useful information. Then suddenly I realized that I had turned of Automatic Updates in windows XP. So I just turned on Automatic Updates. Thereafter I was able to install Windows Live writer without a problem.
So if you are also having the same problem while installing the Windows Live Writer, just go to control panel and open system Properties box by clicking on Systems icon. On System Properties box choose Automatic Update tab and select Automatic option. Now you would be able to install Windows Live applications without a problem.