Even if you have automatic updates set, continue to check Windows Update for any additional ones. They are there. Especially for Vista users. For big downloads and installs, a restore point is always set. You can easily uninstall if any problems arise. View your update history>>Installed Updates. Or you can do a Restore on your system, to get back to the point where Microsoft did not screw up your computer.
Be especially aware of the Service Pack 1 for Vista users.
Hardware people are against installing, because of past problems which arose with XP and those Service Packs.
However, you will see a big range in the amount you have to download & install -- something like anywhere from about 47MG to 500+MG. That's because if you stupidly got the Vista OS early on (like me), you have most of the updates already installed, so your download is smaller.
After the automatic downloads, after checking Windows Update and installing what will not be automatic, run another Windows Update scan of your computer again.
Microsoft is not finished with you. There are more updates. The same ones for XP.
In case any of you are wondering what the heck Microsoft Silverlight is -- it has something to do with integrating animation and video and stuff like that. Be aware that Microsoft collects data on the way this program is used in order to improve the quality.
So, you can always go back to the Optional, but make sure you have those Important and Recommended updates. They keep forever pouring in.
And I need not remind you to keep your Anti-Virus software current and to do back-ups.
Always sumthin'.