I have 3 home systems with XP Pro or XP Media Center -- patch KB913446 failed to install on 2 of the 3. When I reviewed the install history I noticed that this was not the first time that it had not installed; I had at least 2 other installation failures. I downloaded the patch from Microsoft Download Center (http://www.microsoft.com/downloads) and installed it manually with no problems. BTW, if you download it, make sure to select the version that matches your OS.