Hey, I stumbled across this tool the other day and it has been awesome! It has helped me to create a custom install of Windows that included most of the Windows updates. I want to be able to maintain the ULZ file myself though if possible. I have been able to unzip the contents of the ULZ file that comes from the Windows Updates Downloader and take a look inside. I have followed the syntax (I hope anyway) to create a new entry. I used one of the updates that I was notified about when I did a fresh install of the Windows ISO I created. For some reason though, whenever I load in the new ULZ file Windows Updates Downloader crashes afterwards. I have used the validation tool available here http://www.w3.org/2001/03/webdata/xsv .... but it doesn't report any errors. It did the first time I ran it against the file I made, but I corrected it. (I had messed up on the date format) I renamed the ul and ulz update file to: windows-7-sp1-x64-enu-2012-03-7.ul / windows-7-sp1-x64-enu-2012-03-7.ulz (not sure if this is an issue) Here is the entry I entered. I am not really sure even if I should be adding this update. I just know that Windows notified me that I should be installing it <update id="KB2532531" category="1" publishdate="2011-07-11" article="http://support.microsoft.com/kb/2532531"> <title>Security Update for Windows 7 for x64-based Systems (KB2532531)</title> <description>A security issue has been identified that could allow an unauthenticated remote attacker to compromise your system and gain control over it.</description> <filename>Windows6.1-KB2532531-x64.msu</filename> <url>http://download.microsoft.com/download/A/6/0/A60028ED-B27B-420E-AF86-697E41901DBC/Windows6.1-KB2532531-x64.msu</url> </update> I am not sure if I have missed something, but I have been over it a few times and haven't been able to find my error. Is there something else that I am missing? I should almost mention that I changed the "lastupdate" attribute at the top of the file to this - lastupdate="2012-03-7" Thank you, Cheers