There appears to be a problem for a fresh install, and it involves AntiVirus software. Apparently, the Windows Installer as applied directly from SP3 has a problem. After AV software is installed, Windows Updates won't install... they download, but won't install. No error message. Solution... When you are first offered the chance to install SP3, DON'T. Instead, chose "other updates". That way you will get the "Windows Installer 3.1" installed first, followed by a reboot. Then all is OK. You can proceed with SP3 and other updates. This does not affect those who add SP3 from an already updated SP2.. you did the "Win Installer 3.1 + reboot" long ago, and you're still good.