Automatic updates keeps updating same patch
Imagine if an open security issue allowed someone scanning for holes just enough access to your computer to install a keylogger.
That would give the individual at the receiving end access to everything you ever type on your keyboard.
In case you are not familiar with it, WSUS is Microsoft's free patch management tool. If you don't know the difference then you don't do Windows support.
OK, here's the main difference: In addition to OS patches, Microsoft Update takes care of your MS Applications like Office, SQL Server and Exchange. WSUS has a good monitoring and reporting feature that allows me to see at a glance which machines are struggling with the stuff Microsoft is trying to send to it.
I know something is really messed up when I get a 0x8024001D error or some other stupid hex number. At one time I liked Scott Hanselman's method of renaming the c:\windows\Software Distribution\Download to c:\windows\Software Distribution\ Click on "Disable Microsoft Update software and let me use Windows Update only" and then click on "Apply changes now." After the silly thing asks if you are sure (duh! It is simple and fast and has almost always worked for me.
Spreading the checks out over a period of time prevents that from happening. Necessary to prevent unauthorized users from exploiting flaws in Microsoft software to access your computer? The updates that, on most computers, install automatically, often times on Patch Tuesday, are security related patches and are designed to plug recently discovered security holes.